OXYACETYLENE 
WELDING 

AND CUTTING 

ELECTRIC AND 
THE RMIT WEL DING 

MANLY 




Class T~SZZ, 7 
Bnnk -/' 

Copyright W 



COPYRIGHT DEPOSm 



Oxy-Acetylene 
Welding and Cutting 

Electric, Forge and Thermit 
Welding 

Together with Related Methods and 
Materials Used in Metal Working 

And 

The Oxygen Process for 
Removal of Carbon 



HAROLD PI MANLY 

Chief Engineer The American Bureau 
of Engineering 



ILLUSTRATED 



CHICAGO 
FREDERICK J . DRAKE & CO. 

Publishers 



-f5* 



%*\ 



$& 



Copyright 1916 

By Frederick J. Drake & Co. 

Chicago 



6" 



l5\ 



0* 

FEB 3 1916 






9 



JU420871 



PREFACE 

In the preparation of this work, the object has been 
to cover not only the several processes of welding, but 
also those other processes which are so closely allied 
in method and results as to make them a part of the 
whole subject of joining metal to metal with the aid 
of heat. 

The workman who wishes to handle his trade from 
start to finish finds that it is necessary to become 
familiar with certain other operations which precede 
or follow the actual joining of the metal parts, the 
purpose of these operations being to add or retain 
certain desirable qualities in the materials being han- 
dled. For this reason the following subjects have 
been included : Annealing, tempering, hardening, heat 
treatment and the restoration of steel. 

In order that the user may understand the under- 
lying principles and the materials employed in this 
work, much practical information is given on the 
uses and characteristics of the various metals; on the 
production, handling and use of the gases and other 
materials which are a part of the equipment; and on 
the tools and accessories for the production and han- 
dling of these materials. 

An examination will show that the greatest useful- 
ness of this book lies in the fact that all necessary 
information and data has been included in one vol- 
ume, making it possible for the workman to use one 
source for securing a knowledge of both principle 



6 PREFACE 

and practice, preparation and finishing of the work, 
and both large and small repair work as well as manu- 
facturing methods used in metal working. 

An effort has been made to eliminate all matter 
which is not of direct usefulness in practical work, 
while including all that those engaged in this trade 
find necessary. To this end, the descriptions have 
been limited to those methods and accessories which 
are found in actual use today. For the same reason, 
the work includes the application of the rules laid 
down by the insurance underwriters which govern 
this work as well as instructions for the proper care 
and handling of the generators, torches and materials 
found in the shop. 

Special attention has been given to definite direc- 
tions for handling the different metals and alloys 
which must be handled. The instructions have been 
arranged to form rules which are placed in the order 
of their use during the work described and the work 
has been subdivided in such a way that it will be 
found possible to secure information on any one point 
desired without the necessity of spending time in 
other fields. 

The facts which the expert welder and metal- 
worker finds it most necessary to have readily avail- 
able have been secured and prepared especially for 
this work, and those of most general use have been 
combined with the chapter on welding practice to 
which they apply. 

The size of this volume has been kept as small as 
possible, but an examination of the alphabetical index 
will show that the range of subjects and details cov- 
ered is complete in all respects. This has been accom- 
plished through careful classification of the contents 



PREFACE 7 

and the elimination of all repetition and all theoret- 
ical, historical and similar matter that is not abso- 
lutely necessary. 

Free use has been made of the information given 
by those manufacturers who are recognized as the 
leaders in their respective fields, thus insuring that 
the work is thoroughly practical and that it repre- 
sents present day methods and practice. 

The Author. 



CONTENTS 

Chapter I 

PAGE 

Metals and Alloys — Heat Treatment: — The Use and 
Characteristics of the Industrial Alloys and Metal Ele- 
ments — Annealing, Hardening, Tempering and Case Hard- 
ening of Steel 11 

Chapter II 

Welding Materials : — Production, Handling and Use of the 
Gases, Oxygen and Acetylene — Welding Eods — Fluxes — 
Supplies and Fixtures 33 

Chapter III 

Acetylene Generators: — Generator Eequirements and 
Types — Construction — Care and Operation of Generators. 60 

Chapter IY 

Welding Instruments: — Tank and Regulating Valves and 
Gauges — High, Low and Medium Pressure Torches — Cut- 
ting Torches — Acetylene-Air Torches 85 

Chapter V 

Oxy-Acetylene Welding Practice: — Preparation of Work 
— Torch Practice — Control of the Flame — Welding Vari- 
ous Metals and Alloys — Tables of Information Eequired 
in Welding Operations 106 

Chapter VI 

Electric Welding: — Resistance Method — Butt, Spot and 
Lap Welding— Troubles and Remedies — Electric Arc 
Welding ' . 142 



10 CONTENTS 

Chapter VII 

PAGE 

Hand Forging and Welding: — Blacksmithing, Forging 
and Bending — Forge Welding Methods 170 

Chapter VIII 

Soldering, Brazing and Thermit Welding: — Soldering 
Materials and Practice — Brazing — Thermit Welding .... 188 

Chapter IX 
Oxygen Process for Eemoval of Carbon 207 

Index 211 



OXY-ACETYLENE WELDING AND 

CUTTING, ELECTRIC AND 

THERMIT WELDING 



CHAPTER I 

METALS AND THEIR ALLOYS— HEAT TREATMENT 
THE METALS 

Iron. — Iron, in its pure state, is a soft, white, easily 
worked metal. It is the most important of all the 
metallic elements, and is, next to aluminum, the com- 
monest metal found in the earth. 

Mechanically speaking, we have three kinds of iron : 
wrought iron, cast iron and steel. Wrought iron is 
very nearly pure iron; east iron contains carbon and 
silicon, also chemical impurities ; and steel contains a 
definite proportion of carbon, but in smaller quanti- 
ties than cast iron. 

Pure iron is never obtained commercially, the metal 
always being mixed with various proportions of car- 
bon, silicon, sulphur, phosphorus, and other elements, 
making it more or less suitable for different purposes. 
Iron is magnetic to the extent that it is attracted by 
magnets, but it does not retain magnetism itself, as 
does steel. Iron forms, with other elements, many 
important combinations, such as its alloys, oxides, 
and sulphates. 

11 



12 



Y/ELDING 



Cast Iron. — Metallic iron is separated from iron 
ore in the blast furnace (Figure 1), and when allowed 
to run into moulds is called cast iron. This form is 
used for engine cylinders and pistons, for brackets, 
covers, housings and at any point where its brittle- 




Figure 1. — Section Through a Blast Furnace 



ness is not objectionable. Good cast iron breaks with 
a gray fracture, is free from blowholes or roughness, 
and is easily machined, drilled, etc. Cast iron is 
slightly lighter than steel, melts at about 2,400 de- 
grees in practice, is about one-eighth as good an elec- 
trical conductor as copper and has a tensile strength 
of 13,000 to 30,000 pounds per square inch. Its com- 



METALS AND THEIR ALLOYS— HEAT TREATMENT 13 

pressive strength, or resistance to crushing, is very 
great. It has excellent wearing qualities and is not 
easily warped and deformed by heat. Chilled iron 
is cast into a metal mould so that the outside is cooled 
quickly, making the surface very hard and difficult 
to cut and giving great resistance to wear. It is used 
for making cheap gear wheels and parts that must 
withstand surface friction. 

Malleable Cast Iron. — This is often called simply 
malleable iron. It is a form of cast iron obtained by 
removing much of the carbon from cast iron, making 
it softer and less brittle. It has a tensile strength of 
25,000 to 45,000 pounds per square inch, is easily 
machined, will stand a small amount of bending at a 
low red heat and is used chiefly in making brackets, 
fittings and supports where low cost is of considerable 
importance. It is often used in cheap constructions 
in place of steel forgings. The greatest strength of a 
malleable casting, like a steel forging, is in the sur- 
face, therefore but little machining should be done. 

Wrought Iron. — This grade is made by treating the 
cast iron to remove almost all of the carbon, silicon, 
phosphorus, sulphur, manganese and other impuri- 
ties. This process leaves a small amount of the slag 
from the ore mixed with the wrought iron. 

"Wrought iron is used for making bars to be ma- 
chined into various parts. If drawn through the rolls 
at the mill once, while being made, it is called "muck 
bar;" if rolled twice, it is called "merchant bar" 
(the commonest kind) , and a still better grade is made 
by rolling a third time. Wrought iron is being grad- 
ually replaced in use by mild rolled steels. 

Wrought iron is slightly heavier than cast iron, is 
a much better electrical conductor than either cast 



14 WELDING 

iron or steel, has a tensile strength of 40,000 to 60,000 
pounds per square inch and costs slightly more than 
steel. Unlike either steel or cast iron, wrought iron 
does not harden when cooled suddenly from a red heat. 

Grades of Irons. — The mechanical properties of cast 
iron differ greatly according to the amount of other 
materials it contains. The most important of these 
contained elements is carbon, which is present to a 
degree varying from 2 to 5% per cent. When iron 
containing much carbon is quickly cooled and then 
broken, the fracture is nearly white in color and the 
metal is found to be hard and brittle. When the iron 
is slowly cooled and then broken the fracture is gray 
and the iron is more malleable and less brittle. If 
cast iron contains sulphur or phosphorus, it will show 
a white fracture regardless of the rapidity of cooling, 
being brittle and less desirable for general work. 

Steel. — Steel is composed of extremely minute par- 
ticles of iron and carbon, forming a network of layers 
and bands. This carbon is a smaller proportion of the 
metal than found in cast iron, the percentage being 
from T 3 o to 2y 2 per cent. 

Carbon steel is specified according to the number of 
"points" of carbon, a point being one one-hundredth 
of one per cent of the weight of the steel. Steel may 
contain anywhere from 30 to 250 points, which is 
equivalent to saying, anywhere from T 3 o to 2% per 
cent, as above. A 70-point steel would contain 70/100 
of one per cent or T T - of one per cent of carbon by 
weight. The percentage of carbon determines the 
hardness of the steel, also many other qualities, and 
its suitability for various kinds of work. The more 
carbon contained in the steel, the harder the metal 
will be, and, of course, its brittleness increases with 



METALS AND THEIR ALLOYS— HEAT TREATMENT 15 

the hardness. The smaller the grains or particles of 
iron which are separated by the carbon, the stronger 
the steel will be, and the control of the size of these 
particles is the object of the science of heat treatment. 

In addition to the carbon, steel may contain the 
following : 
Silicon, which increases the hardness, brittleness, 

strength and difficulty of working if from 2 to 3 

per cent is present. 
Phosphorus, which hardens and weakens the metal 

but makes it easier to cast. Three-tenths per cent 

of phosphorus serves as a hardening agent and may 

be present in good steel if the percentage of carbon 

is low. More than this weakens the metal. 
Sulphur, which tends to make the metal hard and 

filled with small holes. 
Manganese, which makes the steel so hard and tough 

that it can with difficulty be cut with steel tools. 

Its hardness is not lessened by annealing, and it has 

great tensile strength. 

Alloy steel has a varying but small percentage of 
other elements mixed with it to give certain desired 
qualities. Silicon steel and manganese steel are some- 
times classed as alloy steels. This subject is taken up 
in the latter part of this chapter under Alloys, where 
the various combinations and their characteristics are 
given consideration. 

Steel has a tensile strength varying from 50,000 to 
300,000 pounds per square inch, depending on the 
carbon percentage and the other alloys present, as 
well as upon the texture of the grain. Steel is heavier 
than cast iron and weighs about the same as wrought 
iron. It is about one-ninth as good a conductor of 
electricity as copper. 



16 



WELDING 



Steel is made from cast iron by three principal 
processes: the crucible, Bessemer and open hearth. 

Crucible steel is made by placing pieces of iron in 
a clay or graphite crucible, mixed with charcoal and a 
small amount of any desired alloy. The crucible is 
then heated with coal, oil or gas fires until the iron 
melts, and, by absorbing the desired elements and giv- 
ing up or changing its percentage of carbon, becomes 




Figure 2. — A Bessemer Converter 

steel. The molten steel is then poured from the cru- 
cible into moulds or bars for use. Crucible steel may 
also be made by placing crude steel in the crucibles in 
place of the iron. This last method gives the finest 
grade of metal and the crucible process in general 
gives the best grades of steel for mechanical use. 

Bessemer steel is made by heating iron until all the 
undesirable elements are burned out by air blasts 
which furnish the necessary oxygen. The iron is 
placed in a large retort called a converter (Figure 
2), being poured, while at a melting heat, directly 



METALS AND THEIR ALLOYS— HEAT TREATMENT 17 

from the blast furnace into the converter. While the 
iron in the converter is molten, blasts of air are forced 
through the liquid, making it still hotter and burning 
out the impurities together with the carbon and man- 
ganese. These two elements are then restored to the 
iron by adding spiegeleisen (an alloy of iron, carbon 
and manganese) . A converter holds from 5 to 25 tons 
of metal and requires about 20 minutes to finish a 
charge. This makes the cheapest steel. 




Figure 3. — An Open Hearth Furnace 



Open hearth steel is made by placing the molten 
iron in a receptacle while currents of air pass over it, 
this air having itself been highly heated by just pass- 
ing over white hot brick (Figure. 3). Open hearth 
steel is considered more uniform and reliable than 
Bessemer, and is used for springs, bar steel, tool steel, 
steel plates, etc. 

Aluminum is one of the commonest industrial 
metals. It is used for gear cases, engine crank cases, 
covers, fittings, and wherever lightness and moderate 
strength are desirable. 

Aluminum is about one-third the weight of iron 



18 WELDING 

and about the same weight as glass and porcelain; it 
is a good electrical conductor (about one-half as good 
as copper) ; is fairly strong itself and gives great 
strength to other metals when alloyed with them. One 
of the greatest advantages of aluminum is that it will 
not rust or corrode under ordinary conditions. The 
granular formation of aluminum makes its strength 
very unreliable and it is too soft to resist wear. 

Copper is one of the most important metals used in 
the trades, and the best commercial conductor of elec- 
tricity, being exceeded in this respect only by silver, 
which is but slightly better. Copper is very malleable 
and ductile when cold, and in this state may be easily 
worked under the hammer. Working in this way 
makes the copper stronger and harder, but less duc- 
tile. Copper is not affected by air, but acids cause 
the formation of a green deposit called verdigris. 

Copper is one of the best conductors of heat, as 
well as electricity, being used for kettles, boilers, stills 
and wherever this quality is desirable. Copper is also 
used in alloys with other metals, forming an impor- 
tant part of brass, bronze, german silver, bell metal 
and gun metal. It is about one-eighth heavier than 
steel and has a tensile strength of about 25,000 to 
50,000 pounds per square inch. 

Lead. — The peculiar properties of lead, and espe- 
cially its quality of showing but little action or chem- 
ical change in the presence of other elements, makes 
it valuable under certain conditions of use. Its prin- 
cipal use is in pipes for water and gas, coverings for 
roofs and linings for vats and tanks. It is also used 
to coat sheet iron for similar uses and as an important 
part of ordinary solder. 

Lead is the softest and weakest of all the commer- 



METALS AND THEIR ALLOYS— HEAT TREATMENT 19 

cial metals, being very pliable and inelastic. It should 
be remembered that lead and all its compounds are 
poisonous when received into the system. Lead is 
more than one-third heavier than steel, has a tensile 
strength of only about 2,000 pounds per square inch, 
and is only about one-tenth as good a conductor of 
electricity as copper. 

Zinc. — This is a bluish-white metal of crystalline 
form. It is brittle at ordinary temperatures and be- 
comes malleable at about 250 to 300 degrees Fahren- 
heit, but beyond this point becomes even more brittle 
than at ordinary temperatures. Zinc is practically 
unaffected by air or moisture through becoming cov- 
ered with one of its own compounds which immedi- 
ately resists further action. Zinc melts at low tem- 
peratures, and when heated beyond the melting point 
gives off very poisonous fumes. 

The principal use of zinc is as an alloy with other 
metals to form brass, bronze, german silver and bear- 
ing metals, It is also used to cover the surface of 
steel and iron plates, the plates being then called 
galvanized. 

Zinc weighs slightly less than steel, has a tensile 
strength of 5,000 pounds per square inch, and is not 
quite half as good as copper in conducting electricity. 

Tin resembles silver in color and luster. Tin is 
ductile and malleable and slightly crystalline in form, 
almost as heavy as steel, and has a tensile strength of 
4,500 pounds per square inch. 

The principal use of tin is for protective platings 
on household utensils and in wrappings of tin-foil. 
Tin forms an important part of many alloys such as 
babbitt, Britannia metal, bronze, gun metal and bear- 
ing metals. 



20 WELDING 

Nickel is important in mechanics because of its 
combinations with other metals as alloys. Pure nickel 
is grayish-white, malleable, ductile and tenacious. It 
weighs almost as much as steel and, next to man- 
ganese, is the hardest of metals. Nickel is one of the 
three magnetic metals, the others being iron and co- 
balt. The commonest alloy containing nickel is ger- 
man silver, although one of its most important alloys 
is found in nickel steel. Nickel is about ten per cent 
heavier than steel, and has a tensile strength of 90,000 
pounds per square inch. 

Platinum. — This metal is valuable for two reasons : 
it is not affected by the air or moisture or any ordi- 
nary acid or salt, and in addition to this property it 
melts only at the highest temperatures. It is a fairly 
good electrical conductor, being better than iron or 
steel. It is nearly three times as heavy as steel and 
its tensile strength is 25,000 pounds per square inch. 

alloys 

An alloy is formed by the union of a metal with 
some other material, either metal or non-metallic, 
this union being composed of two or more elements 
and usually brought about by heating the substances 
together until they melt and unite. Metals are al- 
loyed with materials which have been found to give 
to the metal certain characteristics which are desired 
according to the use the metal will be put to. 

The alloys of metals are, almost without exception, 
more important from an industrial standpoint than 
the metals themselves. There are innumerable pos- 
sible combinations, the most useful of which are here 
classed under the head of the principal metal entering 
into their composition. 



METALS AND THEIR ALLOYS— HEAT TREATMENT 21 

Steel. — Steel may be alloyed with almost any of the 
metals or elements, the combinations that have proven 
valuable numbering more than a score. The principal 
ones are given in alphabetical order, as follows : 

Aluminum is added to steel in very small amounts 
for the purpose of preventing blow holes in castings. 

Boron increases the density and toughness of the 
metal. 

Bronze, added by alloying copper, tin and iron, is 
used for gun metal. 

Carbon has already been considered under the head 
of steel in the section devoted to the metals. Carbon, 
while increasing the strength and hardness, decreases 
the ease of forging and bending and decreases the 
magnetism and electrical conductivity. High carbon 
steel can be welded only with difficulty. "When the 
percentage of carbon is low, the steel is called "low 
carbon" or "mild" steel. This is used for rods and 
shafts, and called "machine" steel. When the car- 
bon percentage is high, the steel is called "high 
carbon" steel, and it is used in the shop as tool steel. 
One-tenth per cent of carbon gives steel a tensile 
strength of 50,000 to 65,000 pounds per square inch ; 
two-tenths per cent gives from 60,000 to 80,000 ; four- 
tenths per cent gives 70,000 to 100,000, and six-tenths 
per cent gives 90,000 to 120,000. 

Chromium forms chrome steel, and with the further 
addition of nickel is called chrome nickel steel. This 
increases the hardness to a high degree and adds 
strength without much decrease in ductility. Chrome 
steels are used for high-speed cutting tools, armor 
plate, files, springs, safes, dies, etc. 

Manganese has been mentioned under Steel. Its 
alloy is much used for high-speed cutting tools, the 



22 WELDING 

steel hardening when cooled in the air and being 
called self -hardening. 

Molybdenum is used to increase the hardness to a 
high degree and makes the steel suitable for high- 
speed cutting and gives it self-hardening properties. 

Nickel, with which is often combined chromium, 
increases the strength, springiness and toughness and 
helps to prevent corrosion. 

Silicon has already been described. It suits the 
metal for use in high-speed tools. 

Silver added to steel has many of the properties 
of nickel. 

Tungsten increases the hardness without making 
the steel brittle. This makes the steel well suited for 
gas engine valves as it resists corrosion and pitting. 
Chromium and manganese are often used in com- 
bination with tungsten when high-speed cutting tools 
are made. 

Vanadium as an alloy increases the elastic limit, 
making the steel stronger, tougher and harder. It 
also makes the steel able to stand much bending and 
vibration. 

Copper. — The principal copper alloys include brass, 
bronze, german silver and gun metal. 

Brass is composed of approximately one-third zinc 
and two-thirds copper. It is used for bearings and 
bushings where the speeds are slow and the loads 
rather heavy for the bearing size. It also finds use 
in washers, collars and forms of brackets where the 
metal should be non-magnetic, also for many highly 
finished parts. 

Brass is about one-third as good an electrical con- 
ductor as copper, is slightly heavier than steel and 



METALS AND THEIR ALLOYS— HEAT TREATMENT 23 

has a tensile strength of 15,000 pounds when cast 
and about 75,000 to 100,000 pounds when drawn into 
wire. 

Bronze is composed of copper and tin in various 
proportions, according to the use to which it is to 
be put. There will always be from six-tenths to nine- 
tenths of copper in the mixture. Bronze is used for 
bearings, bushings, thrust washers, brackets and gear 
wheels. It is heavier than steel, about 1/15 as good 
an electrical conductor as pure copper and has a 
tensile strength of 30,000 to 60,000 pounds. 

Aluminum bronze, composed of copper, zinc and 
aluminum has high tensile strength combined with 
ductility and is used for parts requiring this com- 
bination. 

Bearing bronze is a variable material, its composi- 
tion and proportion depending on the maker and the 
use for which it is designed. It usually contains 
from 75 to 85 per cent of copper combined with 
one or more elements, such as tin, zinc, antimony and 
lead. 

White metal is one form of bearing bronze con- 
taining over 80 per cent of zinc together with cop- 
per, tin, antimony and lead. Another form is made 
with nearly 90 per cent of tin combined with copper 
and antimony. 

Gun metal bronze is made from 90 per cent copper 
with 10 per cent of tin and is used for heavy bear- 
ings, brackets and highly finished parts. 

Phosphor bronze is used for very strong castings 
and bearings. It is similar to gun metal bronze, 
except that about 1% P er cen t of phosphorus has 
been added. 

Manganese bronze contains about 1 per cent of 



24 WELDING 

manganese and is used for parts requiring great 
strength while being free from corrosion. 

German silver is made from 60 per cent of copper 
with 20 per cent each of zinc and nickel. Its high 
electrical resistance makes it valuable for regulating 
devices and rheostats. 

Tin is the principal part of babbitt and solder. A 
commonly used babbitt is composed of 89 per cent tin, 
8 per cent antimony and 3 per cent of copper. A 
grade suitable for repairing is made from 80 per 
cent of lead and 20 per cent antimony. This last 
formula should not be used for particular work or 
heavy loads, being more suitable for spacers. In- 
numerable proportions of metals are marketed under 
the name of babbitt. 

Solder is made from 50 per cent tin and 50 per cent 
lead, this grade being called "half-and-half." Hard 
solder is made from two-thirds tin and one-third 
lead. 

Aluminum forms many different alloys, giving in- 
creased strength to whatever metal it unites with. 

Aluminum brass is composed 'of approximately 65 
per cent copper, 30 per cent zinc and 5 per cent alu- 
minum. It forms a metal with high tensile strength 
while being ductile and malleable. 

Aluminum zinc is suitable for castings which must 
be stiff and hard. 

Nickel aluminum has a tensile strength of 40,000 
pounds per square inch. 

Magnalium is a silver-white alloy of aluminum 
with from 5 to 20 per cent of magnesium, forming 
a metal even lighter than aluminum and strong 
enough to be used in making high-speed gasoline 
engines. 



METALS AND THEIR ALLOYS — HEAT TREATMENT 25 
HEAT TREATMENT OF STEEL 

The processes of heat treatment are designed to 
suit the steel for various purposes by changing the 
size of the grain in the metal, therefore the strength; 
and by altering the chemical composition of the al- 
loys in the metal to give it different physical prop- 
erties. Heat treatment, as applied in ordinary shop 
work, includes the three processes of annealing, hard- 
ening and tempering, each designed to accomplish a 
certain definite result. 

All of these processes require that the metal treated 
be gradually brought to a certain predetermined 
degree of heat which shall be uniform throughout the 
piece being handled and, from this point, cooled ac- 
cording to certain rules, the selection of which forms 
the difference in the three methods. 

Annealing. — This is the process which relieves all 
internal strains and distortion in the metal and 
softens it so that it may more easily be cut, machined 
or bent to the required form. In some cases anneal- 
ing is used only to relieve the strains, this being the 
case after forging or welding operations have been 
performed. In other cases it is only desired to soften 
the metal sufficiently that it may be handled easily. 
In some cases both of these things must be accom- 
plished, as after a piece has been forged and must 
be machined. No matter what the object, the pro- 
cedure is the same. 

The steel to be annealed must first be heated to a 
dull red. This heating should be done slowly so 
that all parts of the piece have time to reach the same 
temperature at very nearly the same time. The piece 
may be heated in the forge, but a much better way is 



26 WELDING 

to heat in an oven or furnace of some type where 
the work is protected against air currents, either hot 
or cold, and is also protected against the direct action 
of the fire. 

Probably the simplest of all ovens for small tools is 
made by placing a piece of ordinary gas pipe in the 
fire (Figure 4), and heating until the inside of the 
pipe is bright red. Parts placed in this pipe, after 
one end has been closed, may be brought to the de- 




Figure 4. — A Gaspipe Annealing Oven 

sired heat without danger of cooling draughts or 
chemical change from the action of the fire. More 
elaborate ovens may be bought which use gas, fuel 
oils or coal to produce the heat and in which the 
work may be placed on trays so that the fire will not 
strike directly on the steel being treated. 

If the work is not very important, it may be with- 
drawn from the fire or oven, after heating to the 
desired point, and allowed to cool in the air until all 
traces of red have disappeared when held in a dark 
place. The work should be held where it is reason- 
ably free from cold air currents. If, upon touching 
a pine stick to the piece being annealed, the wood 



METALS AND THEIR ALLOYS— HEAT TREATMENT 27 

does not smoke, the work may then be cooled in 
water. 

Better annealing is secured and harder metal may 
be annealed if the cooling is extended over a number 
of hours by placing the work in a bed of non-heat- 
conducting material, such as ashes, charred bone, 
asbestos fibre, lime, sand or fire clay. It should be 
well covered with the heat retaining material and 
allowed to remain until cool. Cooling may be accom- 
plished by allowing the fire in an oven or furnace 
to die down and go out, leaving the work inside the 
oven with all openings closed. The greater the time 
taken for gradual cooling from the red heat, the 
more perfect will be the results of the annealing. 

While steel is annealed by slow cooling, copper or 
brass is annealed by bringing to a low red heat and 
quickly plunging into cold water. 

Hardening . — Steel is hardened by bringing to a 
proper temperature, slowly and evenly as for an- 
nealing, and then cooling more or less quickly, ac- 
cording to the grade of steel being handled. The 
degree of hardening is determined by the kind of 
steel, the temperature from which the metal is cooled 
and the temperature and nature of the bath into 
which it is plunged for cooling. 

Steel to be hardened is often heated in the fire 
until at some heat around 600 to 700 degrees is 
reached, then placed in a heating bath of molten lead, 
heated mercury, fused cyanate of potassium, etc., the 
heating bath itself being kept at the proper tempera- 
ture by fires acting on it. While these baths have 
the advantage of heating the metal evenly and to 
exactly the temperature desired throughout without 
cny part becoming over or under heated, their dis- 



28 WELDING 

advantages consist of the fact that their materials 
and the fumes are poisonous in most all cases, and if 
not poisonous, are extremely disagreeable. 

The degree of heat that a piece of steel must be 
brought to in order that it may be hardened depends 
on the percentage of carbon in the steel. The greater 
the percentage of carbon, the lower the heat neces- 
sary to harden. 

To find the proper heat from which any steel must 
be cooled, a simple test may be carried out provided 




Figure 5. — Cooling the Test Bar fcr Hardening 

a sample of the steel, about six inches long can be 
secured. One end of this test bar should be heated 
almost to its melting point, and held at this heat 
until the other end just turns red. Now cool the 
piece in water by plunging it so that both ends 
enter at the same time (Figure 5), that is, hold it 
parallel with the surface of the water when plunged 
in. This serves the purpose of cooling each point 
along the bar from a different heat. When it has 
cooled in the water remove the piece and break it at 
short intervals, about y 2 inch, along its length. The 
point along the test bar which was cooled from the 



METALS AND THEIR ALLOYS— HEAT TREATMENT 29 

best possible temperature will show a very fine 
smooth grain and the piece cannot be cut by a file 
at this point. It will be necessary to remember the 
exact color of that point when taken from the fire, 
making another test if necessary, and heat all pieces 
of this same . steel to this heat. It will be necessary 
to have the cooling bath always at the same tempera- 
ture, or the results cannot be alike. 

While steel to be hardened is usually cooled in 
water, many other liquids may be used. If cooled 
in strong brine, the heat will be extracted much 
quicker, and the degree of hardness will be greater. 
A still greater degree of hardness is secured by cool- 
ing in a bath of mercur}^. Care should be used with 
the mercury bath, as the fumes that arise are poi- 
sonous. 

Should toughness be desired, without extreme hard- 
ness, the steel may be cooled in a bath of lard oil, 
neatsfoot oil or fish oil. To secure a result between 
water and oil, it is customary to place a thick layer 
of oil on top of water. In cooling, the piece will pass 
thrugh the oil first, thus avoiding the sudden shock 
of the cold water, yet producing a degree of hard- 
ness almost as great as if the oil were not used. 

It will, of course, be necessary to make a separate 
test for each cooling medium used. If the fracture of 
the test piece shows a coarse grain, the steel was too 
hot at that point; if the fracture can be cut with a 
file, the metal was not hot enough at that point. 

When hardening carbon tool steel its heat should 
be brought to a cherry red, the exact degree of heat 
depending on the amount of carbon and the test made, 
then plunged into water and held there until all 
hissing sound and vibration ceases. Brine may be 



SO WELDING 

used for this purpose ; it is even better than plain 
water. As soon as the hissing stops, remove the 
work from the water or brine and plunge in oil 
for complete cooling. 

In hardening high-speed tool steel, or air hardening 
steels; the tool should be handled as for carbon steel, 
except that after the body reaches a cherry red, the 
cutting point must be quickly brought to a white heat, 




Figure 6. — Cooling the Tool for Tempering 

almost melting, so that it seems ready for welding. 
Then cool in an oil bath or in a current of cool air. 

Hardening of copper, brass and bronze is accom- 
plished by hammering or working them while cold. 

Tempering is the process of making steel tough 
after it has been hardened, so that it will hold a 
cutting edge and resist cracking. Tempering makes 
the grain finer and the metal stronger. It does not 
affect the hardness, but increases the elastic limit 
and reduces the brittleness of the steel. In that tem- 
pering is usually performed immediately after har- 



METALS AND THEIR ALLOYS— HEAT TREATMENT 31 

dening, it might be considered as a continuation of 
the former process. 

The work or tool to be tempered is slowly heated to 
a cherry red and the cutting end is then dipped into 
water to a depth of % to % inch above the point 
(Figure 6). As soon as the point cools, still leaving 
the tool red above the part in water, remove the 
work from the bath and quickly rub the end with a 
fine emery cloth. 

As the heat from the uncooled part gradually heats 
the point again, the color of the polished portion 
changes rapidly. When a certain color is reached, 
the tool should be completely immersed in the water 
until cold. 

For lathe, planer, shaper and slotter tools, this 
color should be a light straw. 

Reamers and taps should be cooled from an ordi- 
nary straw color. 

Drills, punches and wood working tools should 
have a brown color. 

Blue or light purple is right for cold chisels and 
screwdrivers. 

Dark blue should be reached for springs and wood 
saws. 

Darker colors than this, ranging through green and 
gray, denote that the piece has reached its ordinary 
temper, that is, it is partially annealed. 

After properly hardening a spring by dipping in 
lard or fish oil, it should be held over a fire while 
still wet with the oil. The oil takes fire and burns 
off, properly tempering the spring. 

Remember that self -hardening steels must never be 
dipped in water, and always remember for all work 



32 WELDING 

requiring degrees of heat, that the more carbon, the 
less heat. 

Case Hardening. — This is a process for adding 
more carbon to the surface of a piece of steel, so that 
it will have good wear-resisting qualities, while being 
tough and strong on the inside. It has the effect of 
forming a very hard and durable skin on the surface 
of soft steel, leaving the inside unaffected. 

The simplest way, although not the most efficient, 
is to heat the piece to be case hardened to a red 
heat and then sprinkle or rub the part of the surface 
to be hardened with potassium ferrocyanide. This 
material is a deadly poison and should be handled 
with care. Allow the cyanide to fuse on the surface 
of the metal and then plunge into water, brine or 
mercury. Repeating the process makes the surface 
harder and the hard skin deeper each time. 

Another method consists of placing the piece to 
be hardened in a bed of powdered bone (bone which 
has been burned and then powdered) and cover with 
more powdered bone, holding the whole in an iron 
tray. Now heat the tray and bone with the work 
in an oven to a bright red heat for 30 minutes to an 
hour and then plunge the work into water or brine. 






CHAPTER II 

OXY-ACETYLENE WELDING AND CUTTING 
MATEEIALS 

Welding. — Oxy-acetylene welding is an autogenous 
welding process, in which two parts of the same or 
different metals are joined by causing the edges to 
melt and unite while molten without the aid of 
hammering or compression. When cool, the parts 
form one piece of metal. 

The oxy-acetylene flame is made by mixing oxygen 
and acetylene gases in a special welding torch or 
blowpipe, producing, when burned, a heat of 6,300 
degrees, which is more than twice the melting tem- 
perature of the common metals. This flame, while 
being of intense heat, is of very small size. 

Cutting. — The process of cutting metals with the 
flame produced from oxygen and acetylene depends 
on the fact that a jet of oxygen directed upon hot 
metal causes the metal itself to burn away with great 
rapidity, resulting in a narrow slot through the sec- 
tion cut. The action is so fast that metal is not in- 
jured on either side of the cut. 

Carbon Removal. — This process depends on the 
fact that carbon will burn and almost completely 
vanish if the action is assisted with a supply of pure 
oxygen gas. After the combustion is started with 
any convenient flame, it continues as long as carbon 
remains in the path of the jet of oxygen. 

Materials. — For the performance of the above oper- 
ations we require the two gases, oxygen and acetylene, 
to produce the flames; rods of metal which may be 
added to the joints while molten in order to give 

33 



34 WELDING 

the weld sufficient strength and proper form, and va- 
rious chemical powders, called fluxes, which assist 
in the flow of metal and in doing away with many 
of the impurities and other objectionable features. 

Instruments. — To control the combustion of the 
gases and add to the convenience of the operator a 
number of accessories are required. 

The pressure of the gases in their usual containers 
is much too high for their proper use in the torch 
and we therefore need suitable valves which allow the 
gas to escape from the containers when wanted, and 
other specially designed valves which reduce the 
pressure. Hose, composed of rubber and fabric, to- 
gether with suitable connections, is used to carry the 
gas to the torch. 

The torches for welding and cutting form a class of 
highly developed instruments of the greatest accuracy 
in manufacture, and must be thoroughly understood 
by the welder. Tables, stands and special supports 
are provided for holding the work while being welded, 
and in order to handle the various metals and allow 
for their peculiarities while heated use is made of 
ovens and torches for preheating. The operator re- 
quires the protection of goggles, masks, gloves and 
appliances which prevent undue radiation of the heat. 

Torch Practice. — The actual work of welding and 
cutting requires preliminary preparation in the form 
of heat treatment for the metals, including preheat- 
ing, annealing and tempering. The surfaces to be 
joined must be properly prepared for the flame, and 
the operation of the torches for best results requires 
careful and correct regulation of the gases and the 
flame produced. 

Finally, the different metals that are to be welded 



OXY-ACETYLENE WELDING AND CUTTING MATERIALS 35 

require special treatment for each one, depending on 
the physical and chemical characteristics of the ma- 
terial. 

It will thus be seen that the apparently simple 
operations of welding and cutting require special 
materials, instruments and preparation on the part 
of the operator and it is a proved fact that failures, 
which have been attributed to the method, are really 
due to lack of these necessary qualifications. 

OXYGEN 

Oxygen, the gas which supports the rapid combus- 
tion of the acetylene in the torch flame, is one of 
the elements of the air. It is the cause and the active 
agent of all combustion that takes place in the at- 
mosphere. Oxygen was first discovered as a separate 
gas in 1774, when it was produced by heating red 
oxide of mercury and was given its present name by 
the famous chemist, Lavoisier. 

Oxygen is prepared in the laboratory by various 
methods, these including the heating of chloride of 
lime and peroxide of cobalt mixed in a retort, the 
heating of chlorate of potash, and the separation of 
water into its elements, hydrogen and oxygen, by the 
passage of an electric current. While the last process 
is used on a large scale in commercial work, the 
others are not practical for work other than that of 
an experimental or temporary nature. 

This gas is a colorless, odorless, tasteless element. 
It is sixteen times as heavy as the gas hydrogen when 
measured by volume under the same temperature and 
pressure. Under all ordinary conditions oxygen 
remains in a gaseous form, although it turns to a 
liquid when compressed to 4,400 pounds to the square 
inch and at a temperature of 220° below zero. 



36 WELDING 

Oxygen unites with almost every other element, 
this union often taking place with great heat and 
much light, producing flame. Steel and iron will 
burn rapidly when placed in this gas if the combus- 
tion is started with a flame of high heat playing on 
the metal. If the end of a wire is heated bright red 
and quickly plunged into a jar containing this gas, 
the wire will burn away with a dazzling light and be 
entirely consumed except for the molten drops that 
separate themselves. This property of oxygen is used 
in oxy-acetylene cutting of steel. 

The combination of oxygen with other substances 
does not necessarily cause great heat, in fact the com- 
bination may be so slow and gradual that the change 
of temperature can not be noticed. An example of 
this slow combustion, or oxidation, is found in the 
conversion of iron into rust as the metal combines 
with the active gas. The respiration of human beings 
and animals is a form of slow combustion and is the 
source of animal heat. It is a general rule that the 
process of oxidation takes place with increasing rapid- 
ity as the temperature of the body being acted upon 
rises. Iron and steel at a red heat oxidize rapidly 
with the formation of a scale and possible damage to 
the metal. 

Air. — Atmospheric air is a mixture of oxygen and 
nitrogen with traces of carbonic acid gas and water 
vapor. Twenty-one per cent of the air, by volume, 
is oxygen and the remaining seventy-nine per cent 
is the inactive gas, nitrogen. But for the presence 
of the nitrogen, w r hich deadens the action of the other 
gas, combustion would take place at a destructive 
rate and be beyond human control in almost all cases. 
These two gases exist simply as a mixture to form the 



OXY-ACETYLENE WELDING AND CUTTING MATERIALS 37 

air and are not chemically combined. It is there- 
fore a comparatively simple matter to separate them 
with the processes now available. 

Water. — Water is a combination of oxygen and 
hydrogen, being composed of exactly two volumes of 
hydrogen to one volume of oxygen. If these two gases 




Figure 7. — Obtaining Oxygen by Electrolysis 

be separated from each other and then allowed to 
mix in these proportions they unite with explosive 
violence and form water. Water itself may be sepa- 
rated into the gases by any one of several means, 
one making use of a temperature of 2,200° to bring 
about this separation. 

The easiest way to separate water into its two parts 
is by the process called electrolysis (Figure 7). Water, 



38 WELDING 

with which has been mixed a small quantity of acid, 
is placed in a vat through the walls of which enter the 
platinum tipped ends of two electrical conductors, one 
positive and the other negative. 

Tubes are placed directly above these wire ter- 
minals in the vat, one tube being over each electrode 
and separated from each other by some distance. 
With the passage of an electric current from one wire 
terminal to the other, bubbles of gas rise from each 
and pass into the tubes. The gas that comes from 
the negative terminal is hydrogen and that from 
the positive pole is oxygen, both gases being almost 
pure if the work is properly conducted. This method 
produces electrolytic oxygen and electrolytic hydro- 
gen. 

The Liquid Air Process. — While several of the 
foregoing methods of securing oxygen are success- 
ful as far as this result is concerned, they are not 
profitable from a financial standpoint. A process 
for separating oxygen from the nitrogen in the air 
has been brought to a high state of perfection and is 
now supplying a major part of this gas for oxy- 
acetylene welding. It is known as the Linde process 
and the gas is distributed by the Linde Air Products 
Company from its plants and warehouses located in 
the large cities of the country. 

The air is first liquefied by compression, after which 
the gases are separated and the oxygen collected. The 
air is purified and then compressed by successive 
stages in powerful machines designed for this pur- 
pose until it reaches a pressure of about 3,000 pounds 
to the square inch. The large amount of heat pro- 
duced is absorbed by special coolers during the 
process of compression. The highly compressed air is 



OXY-ACETYLENE WELDING AND CUTTING MATERIALS 39 

then dried and the temperature further reduced by 
other coolers. 

The next point in the separation is that at which 
the air is introduced into an apparatus called an in- 
terchanger and is allowed to escape through a valve, 
causing it to turn to a liquid. This liquid air is 
sprayed onto plates and as it falls, the nitrogen re- 
turn to its gaseous state and leaves the oxygen to 
run to the bottom of the container. This liquid 
oxygen is then allowed to return to a gas and is 
stored in large gasometers or tanks. 

The oxygen gas is taken from the storage tanks and 
compressed to approximately 1,800 pounds to the 
square inch, under which pressure it is passed into 
steel cylinders and made ready for delivery to the 
customer. This oxygen is guaranteed to be ninety- 
seven per cent pure. 

Another process, known as the Hildebrandt process, 
is coming into use in this country. It is a later process 
and is used in Germany to a much greater extent than 
the Linde process. The Superior Oxygen Co. has 
secured the American rights and has established sev- 
eral plants. 

Oxygen Cylinders. — Two sizes of cylinders^are in 
use, one containing 100 cubic feet of gas when it is 
at atmospheric pressure and the other containing 250 
cubic feet under similar conditions. The cylinders 
are made from one piece of steel and are without 
seams. These containers are tested at double the pres- 
sure of the gas contained to insure safety while 
handling. 

One hundred cubic feet of oxygen weighs nearly 
nine pounds (8.921), and therefore the cylinders 
will weigh prr fically nine pounds more when full 



40 



WELDING 



than after emptying, if of the 100 cnbic feet size. 
The large cylinders weigh about eighteen and one- 
quarter pounds more when full than when empty, 
making approximately 212 pounds empty and 230 
pounds full. 

The following table gives the number of cubic feet 
of oxygen remaining in the cylinders according to 
various gauge pressures from an initial pressure of 
1,800 pounds. The amounts given are not exactly 
correct as this would necessitate lengthy calculations 
which would not make great enough difference to 
affect the practical usefulness of the table : 





Cylinder of 100 Cu. Ft. 


Capacity at 68° 


Fahr. 


Gauge 




Volume 


Gauge 


Volume 


Pressure 




Remaining 


Pressure 


Remaining 


1800 




100 


700 


39 


1620 




90 


500 


28 


1440 




80 


300 


17 


1260 




70 


100 


6 


1080 




60 


18 


1 


900 




50 


9 


Y2 




Cylinder 


of 250 Cu. Ft. 


Capacity at 68° 


Fahr. 


Gauge 




Volume 


Gauge 


Volume 


Pressure 




Remaining 


Pressure 


Remaining 


1800 




250 


700 


97 


1620 




225 


500 


70 


1440 




200 


300 


42 


1260 




175 


100 


15 


1080 




150 


18 


8 


900 




125 


9 


1% 



The temperature of the cylinder affects the pressure 
in a large degree, the pressure increasing with a rise 
in temperature and falling with a fall in temperature. 
The variation for a 100 cubic foot cylinder at various 
temperatures is given in the following tabulation: 



OXY-ACETYLENE WELDING AND CUTTING MATERIALS 41 

At 150° Fahr 2090 pounds. 

At 100° Fahr 1912 pounds. 

At 80° Fahr 1844 pounds. 

At 68° Fahr 1800 pounds. 

At 50° Fahr 1736 pounds. 

At 32° Fahr 1672 pounds. 

At Fahr 1558 pounds. 

At— 10° Fahr 1522 pounds. 

Chlorate of Potash Method. — In spite of its higher 
cost and the inferior gas produced, the chlorate of 
potash method of producing oxygen is used to a 




\ 






1 


1 




1 




_ 







WASHERS 

Figure 8. — Oxygen from Chlorate of Potash 

limited extent when it is impossible to secure the gas 
in cylinders. 

An iron retort (Figure 8) is arranged to receive 
about fifteen pounds of chlorate of potash mixed with 
three pounds of manganese dioxide, after which the 
cylinder is closed with a tight cap, clamped on. This 
retort is carried above a burner using fuel gas or 
other means of generating heat and this burner is 
lighted after the chemical charge is mixed and com- 
pressed in the tube. 

The generation of gas commences and the oxygen is 
led through water baths which wash and cool it 



42 WELDING 

before storing in a tank connected with the plant. 
From this tank the gas is compressed into portable 
cylinders at a pressure of about 300 pounds to the 
square inch for use as required in welding operations. 

Each pound of chlorate of potash liberates about 
three cubic feet of oxygen, and taking everything into 
consideration, the cost of gas produced in this way is 
several times that of the purer product secured by 
the liquid air process. 

These chemical generators are oftentimes a source 
of great danger, especially when used with or near 
the acetylene gas generator, as is sometimes the case 
with cheap portable outfits. Their use should not be 
tolerated when any other method is available, as the 
danger from accident alone should prohibit the prac- 
tice except when properly installed and cared for 
away from other sources of combustible gases. 

ACETYLENE 

In 1862 a chemist, Woehler, announced the dis- 
covery of the preparation of acetylene gas from cal- 
cium carbide, which he had made by heating to a high 
temperature a mixture of charcoal with an alloy of 
zinc and calcium. His product would decompose 
water and yield the gas. For nearly thirty years these 
substances were neglected, with the result that acety- 
lene was practically unknown, and up to 1892 an 
acetylene flame was seen by very few persons and 
its possibilities were not dreamed of. With the de- 
velopment of the modern electric furnace the possi- 
bility of calcium carbide as a commercial product 
became known. 

In the above year, Thomas L. Willson, an electrical 
engineer of Spray, North Carolina, was experiment- 



OXY-ACETYLENE WELDING AND CUTTING MATERIALS 43 

ing in an attempt to prepare metallic calcium, for 
which purpose he employed an electric furnace oper- 
ating on a mixture of lime and coal tar with about 
ninety-five horse power. The result was a molten 
mass which became hard and brittle when cool. This 
apparently useless product was discarded and thrown 
in a nearby stream, when, to the astonisment of on- 
lookers, a large volume of gas was immediately lib- 
erated, which, when ignited, burned with a bright 
and smoky flame and gave off quantities of soot. 
The solid material proved to be calcium carbide and 
the gas acetylene. 

Thus, through the incidental study of a by-product, 
and as the result of an accident, the possibilities in 
carbide were made known, and in the spring of 1895 
the first factory in the world for the production of 
this substance was established by the Willson Alumi- 
num Company. 

When water and calcium carbide are brought to- 
gether an action takes place which results in the for- 
mation of acetylene gas and slaked lime. 

CARBIDE 

Calcium carbide is a chemical combination of the 
elements carbon and calcium, being dark brown, black 
or gray with sometimes a blue or red tinge. It 
looks like stone and will only burn when heated with 
oxygen. 

Calcium carbide may be preserved for any length 
of time if protected from the air, but the ordinary 
moisture in the atmosphere gradually affects it until 
nothing remains but slaked lime. It always possesses 
a penetrating odor, which is not due to the carbide 
itself but to the fact that it is being constantly af- 



44 WELDING 

fected by moisture and producing small quantities of 
acetylene gas. 

This material is not readily dissolved by liquids, 
but if allowed to come in contact with water, a de- 
composition takes place with the evolution of large 
quantities of gas. Carbide is not affected by shock, 
jarring or age. 

A pound of absolutely pure carbide will yield five 
and one-half cubic feet of acetylene. Absolute purity 
cannot be attained commercially, and in practice good 
carbide will produce from four and one-half to five 
cubic feet for each pound used. 

Carbide is prepared by fusing lime and carbon in 
the electric furnace under a heat in excess of 6,000° 
Fahrenheit. These materials are among the most diffi- 
cult to melt that are known. Lime is so infusible that 
it is frequently employed for the materials of cruci- 
bles in which the highest melting metals are fused, 
and for the pencils in the calcium light because it will 
stand extremely high temperatures. 

Carbon is the material employed in the manufac- 
ture of arc light electrodes and other electrical appli- 
ances that must stand extreme heat. Yet these two 
substances are forced into combination in the manu- 
facture of calcium carbide. It is the excessively high 
temperature attainable in the electric furnace that 
causes this combination and not any effect of the elec- 
tricity other than the heat produced. 

A mixture of ground coke and lime is introduced 
into the furnace through which an electric arc has 
been drawn. The materials unite and form an ingot 
of very pure carbide surrounded by a crust of less 
purity. The poorer crust is rejected in breaking up 
the mass into lumps which are graded according to 



OXY-ACETYLENE WELDING AND CUTTING MATERIALS 45 

their size. The largest size is 2 by 3V 2 inches and 
is called "lump," a medium size is y 2 by 2 inches and 
is called ' ' egg, ' ' an intermediate size for certain types 
of generators is % by ±14 inches and called "nut," 
and the finely crushed pieces for use in still other 
types of generators are 1/12 by 14 inch in size and 
are called ' ' quarter. ' ' Instructions as to the size best 
suited to different generators are furnished by the 
makers of those instruments. 

These sizes are packed in air-tight sheet steel drums 
containing 100 pounds each. The Union Carbide 
Company of Chicago and New York, operating under 
patents, manufactures and distributes the supply of 
calcium carbide for the entire United States. Plants 
for this manufacture are established at Niagara Falls, 
New York, and Sault Ste. Marie, Michigan. This 
company maintains a system of warehouses in more 
than one hundred and ten cities, where large stocks 
of all sizes are carried. 

The National Board of Fire Underwriters gives the 
following rules for the storage of carbide : 

Calcium carbide in quantities not to exceed six 
hundred pounds may be stored, when contained in 
approved metal packages not to exceed one hundred 
pounds each, inside insured property, provided that 
the place of storage be dry, waterproof and well ven- 
tilated and also provided that all but one of the 
packages in any one building shall be sealed and 
that seals shall not be broken so long as there is car- 
bide in excess of one pound in any other unsealed 
package in the building. 

Calcium carbide in quantities in excess of six hun- 
dred pounds must be stored above ground in detached 
buildings, used exclusively for the storage of cal- 



46 WELDING 

cium carbide, in approved metal packages, and such 
buildings shall be constructed to be dry, waterproof 
and well ventilated. 

Properties of Acetylene. — This gas is composed of 
twenty-four parts of carbon and two parts of hydro- 
gen by weight and is classed with natural gas, petro- 
leum, etc., as one of the hydrocarbons. This gas con- 
tains the highest percentage of carbon known to exist 
in any combination of this form and it may there- 
fore be considered as gaseous carbon. Carbon is the 
fuel that is used in all forms of combustion and is 
present in all fuels from whatever source or in what- 
ever form. Acetylene is therefore the most power- 
ful of all fuel gases and is able to give to the torch 
flame in welding the highest temperature of any 
flame. 

Acetylene is a colorless and tasteless gas, possessed 
of a peculiar and penetrating odor. The least trace 
in the air of a room is easily noticed, and if this odor 
is detected about an apparatus in operation, it is 
certain to indicate a leakage of gas through faulty 
piping, open valves, broken hose or otherwise. This 
leakage must be prevented before proceeding with the 
work to be done. 

All gases which burn in air will, when mixed with 
air previous to ignition, produce more or less vio- 
lent explosions, if fired. To this rule acetylene is no 
exception. One measure of acetylene and twelve and 
one-half of air are required for complete combustion ; 
this is therefore the proportion for the most perfect 
explosion. This is not the only possible mixture that 
will explode, for all proportions from three to thirty 
per cent of acetylene in air will explode with more 
or less force if ignited. 



OXY-ACETYLENE WELDING AND CUTTING MATERIALS 47 

The igniting point of acetylene is lower than that 
of coal gas, being about 900 degrees Fahrenheit as 
against eleven hundred degrees for coal gas. The 
gas issuing from a torch will ignite if allowed to play 
on the tip of a lighted cigar. 

It is still further true that acetylene, at some pres- 
sures, greater than normal, has under most favorable 
conditions for the effect, been found to explode ; yet 
it may be stated with perfect confidence that under no 
circumstances has anyone ever secured an explosion 
in it when subjected to pressures not exceeding fif- 
teen pounds to the square inch. 

Although not exploded by the application of high 
heat, acetylene is injured by such treatment. It is 
partly converted, by high heat, into other compounds, 
thus lessening the actual quantity of the gas, wasting 
it and polluting the rest by the introduction of sub- 
stances which do not belong there. These compounds 
remain in part with the gas, causing it to burn with 
a persistent smoky flame and with the deposit of 
objectionable tarry substances. Where the gas is gen- 
erated without undue rise of temperature these diffi- 
culties are avoided. 

Purification of Acetylene. — Impurities in this gas 
are caused by impurities in the calcium carbide from 
which it is made or by improper methods and lack of 
care in generation. Impurities from the material 
will be considered first. 

Impurities in the carbide may be further divided 
into two classes: those which exert no action on water 
and those which act with the water to throw off 
other gaseous products which remain in the acetylene. 
Those impurities which exert no action on the water 
consist of coke that has not been changed in the 



48 WELDING 

furnace and sand and some other substances which 
are harmless except that they increase the ash left 
after the acetylene has been generated. 

An analysis of the gas coming from a typical gen- 
erator is as follows: 

Per cent 

Acetylene 99.36 

Oxygen 08 

Nitrogen 11 

Hydrogen 06 

Sulphuretted Hydrogen 17 

Phosphoretted Hydrogen 04 

Ammonia 10 

Silicon Hydride '. 03 

Carbon Monoxide 01 

Methane ' 04 

The oxygen, nitrogen, hydrogen, methane and car- 
bon monoxide are either harmless or are present in 
such small quantities as to be neglected. The phos- 
phoretted hydrogen and silicon hydride are self- 
inflammable gases when exposed to the air, but their 
quantity is so very small that this possibility may be 
dismissed. The ammonia and sulphuretted hydrogen 
are almost entirely dissolved by the water used in 
the gas generator. The surest way to avoid impure 
gas is to use high-grade calcium carbide in the gener- 
ator and the carbide of American manufacture is 
now so pure that it never causes trouble. 

The first and most important purification to which 
the gas is subjected is its passage through the body 
of water in the generator as it bubbles to the top. 
It is then filtered through felt to remove the solid 



OXY-ACETYLENE WELDING AND CUTTING MATERIALS 49 

particles of lime dust and other impurities which, 
float in the gas. 

Further purification to remove the remaining am- 
monia, sulphuretted hydrogen and phosphorus con- 
taining compounds is accomplished by chemical 
means. If this is considered necessary it can be easily 
accomplished by readily available purifying appa- 
ratus which can be attached to any generator or in- 
serted between the generator and torch outlets. The 
following mixtures have been used. 

"Heratol," a solution of chromic acid or sulphuric 
acid absorbed in porous earth. 

"Acagine," a mixture of bleaching powder with 
fifteen per cent of lead chromate. 

"Pnratylene," a mixture of bleaching powder and 
hydroxide of lime, made very porous, and containing 
from eighteen to twenty per cent of active chlorine. 

"Frankoline," a mixture of cuprous and ferric 
chlorides dissolved in strong hydrochloric acid ab- 
sorbed in infusorial earth. 

A test for impure acetylene gas is made by placing 
a drop of ten per cent solution of silver nitrate on 
a white blotter and holding the paper in a stream of 
gas coming from the torch tip. Blackening of the 
paper in a short length of time indicates impurities. 

Acetylene in Tanks. — Acetylene is soluble in water 
to a very limited extent, too limited to be of prac- 
tical use. There is only one liquid that possesses 
sufficient power of containing acetylene in solution 
to be of commercial value, this being the liquid ace- 
tone. Acetone is produced in various ways, often- 
times from the distillation of wood. It is a trans- 
parent, colorless liquid that flows with ease. It boils 
at 133° Fahrenheit, is inflammable and burns with 



50 WELDING 

a luminous flame. It has a peculiar but rather agree- 
able odor. 

Acetone dissolves twenty-four times its own bulk of 
acetylene at ordinary atmospheric pressure. If this 
pressure is increased to two atmospheres, 14.7 pounds 
above ordinary pressure, it will dissolve just twice as 
much of the gas and for each atmosphere that the 
pressure is increased it will dissolve as much more. 

Ii acetylene be compressed above fifteen pounds 
per square inch at ordinary temperature without first 
being dissolved in acetone a danger is present of self- 
ignition. This danger, while practically nothing at 
fifteen pounds, increases with the pressure until at 
forty atmospheres it is very explosive. Mixed with 
acetone, the gas loses this dangerous property and is 
safe for handling and transportation. As acetylene is 
dissolved in the liquid the acetone increases its vol- 
ume slightly so that when the gas has been drawn out 
of a closed tank a space is left full of free acetylene. 

This last difficulty is removed by first filling the 
cylinder or tank with some porous material, such as 
asbestos, wood charcoal, infusorial earth, etc. As- 
bestos is used in practice and by a system of packing 
and supporting the absorbent material no space is 
left for the free gas, even when the acetylene has 
been completely withdrawn. 

The acetylene is generated in the usual way and is 
washed, purified and dried. Great care is used to 
make the gas as free as possible from all impurities 
and from air. The gas is forced into containers 
filled with acetone as described and is compressed to 
one hundred and fifty pounds to the square inch. 
From these tanks it is transferred to the smaller port- 
able cvlinders for consumers' use. 



OXY-ACETYLENE WELDING AND CUTTING MATERIALS 51 

The exact volume of gas remaining in a cylinder at 
atmospheric temperature may be calculated if the 
weight of the cylinder empty is known. One pound 
of the gas occupies 13.6 cubic feet, so that if the 
difference in weight between the empty cylinder and 
the one considered be multiplied by 13.6, the result 
will be the number of cubic feet of gas contained. 

The cylinders contain from 100 to 500 cubic feet 
of acetylene under pressure. They cannot be filled 
with the ordinary type of generator as they require 
special purifying and compressing apparatus, which 
should never be installed in any building where other 
work is being carried on, or near other buildings 
which are occupied, because of the danger of ex- 
plosion. 

Dissolved acetylene is manufactured by the Prest- 
O-Lite Company, the Commercial Acetylene Com- 
pany and the Searchlight Gas Company and is dis- 
tributed from warehouses in various cities. 

These tanks should not be discharged at a rate per 
hour greater than one-seventh of their total capacity, 
that is, from a tank of 100 cubic feet capacity, the 
discharge should not be more than fourteen cubic 
feet .per hour. If discharge is carried on at an ex- 
cessive rate the acetone is drawn out with the gas 
and reduces the heat of the welding flame. 

For this reason welding should not be attempted 
with cylinders designed for automobile and boat 
lighting. When the work demands a greater delivery 
than one of the larger tanks will give, two or more 
tanks may be connected with a special coupler such as 
may be secured from the makers and distributers of 
the gas. These couplers may be arranged for two, 
three, four or five tanks in one battery by removing 



52 WELDING 

the plugs on the body of the coupler and attaching 
additional connecting pipes. The coupler body car- 
ries a pressure gauge and the valve for controlling 
the pressure of the gas as it flows to the welding 
torches. The following capacities should be provided 
for: 

Acetylene Consumption Combined Capacity of 

of Torches per Hour Cylinders in Use 

Up to 15 feet 100 cubic feet 

16 to 30 feet 200 cubic feet 

31 to 45 feet 300 cubic feet 

46 to 60 feet 400 cubic feet 

61 to 75 feet. 500 cubic feet 

WELDING RODS 

The best welding cannot be done without using the 
best grade of materials, and the added cost of these 
materials over less desirable forms is so slight when 
compared to the quality of work performed and the 
waste of gases with inferior supplies, that it is very 
unprofitable to take any chances in this respect. The 
makers of welding equipment carry an assortment of 
supplies that have been standardized and that may 
be relied upon to produce the desired result when 
properly used. The safest plan is to secure this class 
of material from the makers. 

"Welding rods, or welding sticks, are used to supply 
the additional metal required in the body of the weld 
to replace that broken or cut away and also to add 
to the joint whenever possible so that the work may 
have the same or greater strength than that found in 
the original piece. A rod of the same material as 



OXY-ACETYLENE WELDING AND CUTTING MATERIALS 53 

that being welded is used when both parts of the work 
are the same. When dissimilar metals are to be joined 
rods of a composition suited to the work are em- 
ployed. 

These filling rods are required in all work except 
steel of less than 16 gauge. Alloy iron rods are used 
for cast iron. These rods have a high silicon content, 
the silicon reacting with the carbon in the iron to 
produce a softer and more easily machined weld than 
would otherwise be the case. These rods are often 
made so that they melt at a slightly lower point than 
cast iron. This is done for the reason that when the 
part being welded has been brought to the fusing heat 
by the torch, the filling material can be instantly 
melted in without allowing the parts to cool. The 
metal can be added faster and more easily controlled. 

Rods or wires of Norway iron are used for steel 
welding in almost all cases. The purity of this grade 
of iron gives a homogeneous, soft weld of even texture, 
great ductility and exceptionally good machining 
qualities. For welding heavy steel castings, a rod of 
rolled carbon steel is employed. For working on high 
carbon steel, a rod of the steel being welded must be 
employed and for alloy steels, such as nickel, man- 
ganese, vanadium, etc., special rods of suitable alloy 
composition are preferable. 

Aluminum welding rods are made from this metal 
alloyed to give the even flowing that is essential. 
Aluminum is one of the most difficult of all the metals 
to handle in this work and the selection of the proper 
rod is of great importance. 

Brass is filled with brass wire when in small cast- 
ings and sheets. For general work with brass castings, 
manganese bronze or Tobin bronze may be used. 



54 WELDING 

Bronze is welded with manganese bronze or Tobin 
bronze, while copper is filled with copper wire. 

These welding- rods should always be used to fill 
the weld when the thickness of material makes their 
employment necessary, and additional metal should 
always be added at the weld when possible as the 
joint cannot have the same strength as the original 
piece if made or dressed off flush with the surfaces 
around the weld. This is true because the metal 
welded into the joint is a casting and will never have 
more strength than a casting of the material used, for 
filling. 

Great care should be exercised when adding metal 
from welding rods to make sure that no metal is" 
added at a point that is not itself melted and molten 
when the addition is made. When molten metal is 
placed upon cooler surfaces the result is not a weld 
but merely a sticking together of the two parts with- 
out any strength in the joint, 

FLUXES 

Difficulty would be experienced in welding with 
only the metal and rod to work with because of the 
scale that forms on many materials under heat, the 
oxides of other metals and the impurities found in 
almost all metals. These things tend to prevent a 
perfect joining of the metals and some means are 
necessary to prevent their action. 

Various chemicals, usually in powder form, are 
used to accomplish the result of cleaning the weld 
and making the work of the operator less difficult. 
They are called fluxes. 

A flux is used to float off physical impurities from 
the molten metal; to furnish a protecting coating 



OXY-ACETYLENE WELDING AND CUTTING MATERIALS 55 

around the weld; to assist in the removal of any ob- 
jectionable oxide of the metals being handled; to 
lower the temperature at which the materials Aoav ; to 
make a cleaner weld and to produce a better quality 
of metal in the finished work. 

The flux must be of such composition that it will 
accomplish the desired result without introducing 
new difficulties. They may be prepared by the oper- 
ator in many cases or may be secured from the mak- 
ers of welding apparatus, the same remarks applying 
to their quality as were made regarding the welding 
rods, that is, only the best should be considered. 

The flux used for cast iron should have a softening 
effect and should prevent burning of the metal. In 
many cases it is possible and even preferable to weld 
cast iron without the use of a flux, and in any event 
the smaller the quantity used the better the result 
should be. Flux should not be added just before the 
completion of the work because the heat will not have 
time to drive the added elements out of the metal or 
to incorporate them with the metal properly. 

Aluminum should never be welded without using 
a flux because of the oxide formed. This oxide, called 
alumina, does not melt until a heat of 5,000° Fahren- 
heit is reached, four times the heat needed to melt the 
aluminum itself. It is necessary that this oxide be 
broken down or dissolved so that the aluminum may 
have a chance to flow together. Copper is another 
metal that requires a flux because of its rapid oxida- 
tion under heat. 

While the flux is often thrown or sprinkled along 
the break while welding, much better results will be 
obtained by dipping the hot end of the welding rod 
into the flux whenever the work needs it. Suffi- 



56 WELDING 

cient powder will stick on the end of the rod for all 
purposes, and with some fluxes too much will adhere. 
Care should always be used to avoid the application 
of excessive flux, as this is usually worse than using 
too little. 

SUPPLIES AND FIXTURES 

Goggles. — The oxy-acetylene torch should not be 
used without the protection to the eyes afforded by 
goggles. These not only relieve unnecessary strain, 
but make it much easier to watch the exact progress 
of the work with the molten metal The difficulty of 
protecting the sight while welding is even greater 
than when cutting metal with the torch. 

Acetylene gives a light which is nearest to sunlight 
of any artificial illuminant. But for the fact that 
this gas light gives a little more green and less blue 
in its composition, it would be the same in quality 
and practically the same in intensity. This light 
from the gas is almost absent during welding, being 
lost with the addition of the extra oxygen needed to 
produce the welding heat. The light that is dan- 
gerous comes from the molten metal which flows 
under the torch at a bright white heat. 

Goggles for protection against this light and the 
heat that goes with it may be secured in various 
tints, the darker glass being for welding and the 
lighter for cutting. Those having frames in which 
the metal parts do not touch the flesh directly are 
most desirable because of the high temperature 
reached by these parts. 

Gloves. — While not as necessary as are the goggles, 
gloves are a convenience in many cases. Those in 
which leather touches the hands directly are really 



OXY-ACETYLENE WELDING AND CUTTING MATERIALS 57 

of little value as the heat that protection is desired 
against makes the leather so hot that nothing is gained 
in comfort. Gloves are made with asbestos cloth, 
which are not open to this objection in so great a 
degree. 




Figure 



Stand 



Tables and Stands. — Tables for holding work while 
being welded (Figure 9) are usually made from 
lengths of angle steel welded together. The top should 
be rectangular, about two feet wide and two and one- 
half feet long. The legs should support the working 
surface at a height of thirty-two to thirty-six inches 
from the floor. Metal lattice work may be fastened 
or laid in the top framework and used to support a 
layer of firebrick bound together with a mixture of 
one-third cement and two-thirds fireclay. The piece 
being welded is braced and supported on this table 
with pieces of firebrick so that it will remain station- 
ary during the operation. 



58 WELDING 

Holders for supporting the tanks of gas may be 
made or purchased in forms that rest directly on the 
floor or that are mounted on wheels. These holders 
are quite useful where the floor or ground is very 
uneven. 

Hose. — All permanent lines from tanks and gener- 
ators to the torches are made with piping rigidly sup- 
ported, but the short distance from the end of the 
pipe line to the torch itself is completed with a flexi- 
ble hose so that the operator may be free in his move- 
ments while welding. An accident through which the 
gases mix in the hose and are ignited will burst this 
part of the equipment, with more or less painful re- 
sults to the person handling it. For that reason it is 
well to use hose with great enough strength to with- 
stand excessive pressure. 

A poor grade of hose will also break down inside 
and clog the flow of gas, both through itself and 
through the parts of the torch. To avoid outside dam- 
age and cuts this hose is sometimes encased with 
coiled sheet metal. Hose may be secured with a burst- 
ing strength of more than 1,000 pounds to the square 
inch. Many operators prefer to distinguish between 
the oxygen and acetylene lines by their color and to 
allow this, red is used for the oxygen and black for 
acetylene. 

Other Materials. — Sheet asbestos and asbestos fibre 
in flakes are used to cover parts of the work while pre- 
paring them for welding and during the operation 
itself. The flakes and small pieces that become de- 
tached from the large sheets are thrown into a bin 
where the completed small work is placed to allow 
slow and even cooling while protected by the asbestos. 

Asbestos fibre and also ordinary fireclay are often 



OXY-ACETYLENE WELDING AND CUTTING MATERIALS 59 

used to make a backing or mould into a form that 
may be placed behind aluminum and some other 
metals that flow at a low heat and which are accord- 
ingly difficult to handle under ordinary methods. 
This forms a solid mould into which the metal is prac- 
tically cast as melted by the torch so that the desired 
shape is secured without danger of the walls of metal 
breaking through and flowing away. 

Carbon blocks and rods are made in various shapes 
and sizes so that they may be used to fill threaded 
holes and other places that it is desired to protect 
during welding. These may be secured in rods of 
various diameters up to one inch and in blocks of 
several different dimensions. 



CHAPTER III 
ACETYLENE GENERATORS 

Acetylene generators used for producing the gas 
from the action of water on calcium carbide are di- 
vided into three principal classes according to the 
pressure under which they operate. 

Low pressure generators are designed to operate at 
one pound or less per square inch. Medium pressure 
systems deliver the gas at not to exceed fifteen pounds 
to the square inch while high pressure types furnish 
gas above fifteen pounds per square inch. High 
pressure systems are almost unknown in this country, 
the medium pressure type being often referred to as 
"high pressure." 

Another important distinction is formed by the 
method of bringing the carbide and water together. 
The majority of those now in use operate by. drop- 
ping small quantities of carbide into a large volume 
of water; allowing the generated gas to bubble up 
through the water before being collected above the 
surface. This type is known as the "carbide to 
water" generator. 

A less used type brings a measured and small quan- 
tity of water to a comparatively large body of the 
carbide, the gas being formed and collected from 
the chamber in which the action takes place. This 
is called the "water to carbide" type. Another way 
of expressing the difference in feed is that of desig- 
nating the two types as "carbide feed" for the former 
and ' ' water feed ' ' for the latter. 

60 



ACETYLENE GENERATORS 61 

A further division of the carbide to water ma- 
chines is made by mentioning the exact method of 
feeding the carbide One type, called ' ' gravity feed ' ' 
operates by allowing the carbide to escape and fall by 
the action of its own weight, or gravity; the other 
type, called "forced feed," includes a separate mech- 
anism driven by power This mechanism feeds defi- 
nite amounts of the carbide to the water as required 
by the demands on the generator. The action of 
either feed is controlled by the withdrawal of gas 
from the generator, the aim being to supply suffi- 
cient carbide to maintain a nearly constant supply. 

Generator Requirements. — The qualities of a good 
generator are outlined as follows :* 

It must allow no possibility of the existence of an 
explosive mixture in any of its parts at any time. It 
is not enough to argue that a mixture, even if it exists, 
cannot be exploded unless kindled. It is necessary to 
demand that a dangerous mixture can at no time be 
formed, even if the machine is tampered with by an 
ignorant person. The perfect machine must be so 
constructed that it shall be impossible at any time, 
under any circumstances, to blow it up. 

It must insure cool generation. Since this is a rela- 
tive term, all machines being heated somewhat dur- 
ing the generation of gas, this amounts to saying that 
a machine must heat but little. A pound of carbide 
decomposed by water develops the same amount of 
heat under all circumstances, but that heat can be 
allowed to increase locally to a high point, or it can 
be equalized by water so that no part of the material 
becomes heated enough to do damage. 



See Pond's "Calcium Carbide and Acetylene.' 



62 WELDING 

It must be well constructed. A good generator 
does not need, perhaps, to be ' ' built like a watch, ' ' but 
it should be solid, substantial and of good material. 
It should be built for service, to last and not simply 
to sell; anything short of this is to be avoided as 
unsafe and unreliable. 

It must be simple. The more complicated the ma- 
chine the sooner it will get out of order. Understand 
your generator. Know what is inside of it and be- 
ware of an apparatus, however attractive its exterior, 
whose interior is filled with pipes and tubes, valves 
and diaphragms whose functions you do not per- 
fectly understand. 

It should be capable of being cleaned and re- 
charged and of receiving all other necessary atten- 
tion without loss of gas, both for economy's sake, and 
more particularly to avoid danger of fire. 

It should require little attention. All machines 
have to be emptied and recharged periodically; but 
the more this process is simplified and the more 
quickly this can be accomplished, the better. 

It should be provided with a suitable indicator to 
designate how low the charge is in order that the 
refilling may be done in good season. 

It should completely use up the carbide, generat- 
ing the maximum amount of gas. 

Overheating. — A large amount of heat is liberated 
when acetylene gas is formed from the union of cal- 
cium carbide and water. Overheating during this 
process, that is to say, an intense local heat rather 
than a large amount of heat well distributed, brings 
about the phenomenon of polymerization, converting 
the gas, or part of it, into oily matters, which can do 
nothing but harm. This tarry mass coming through 



ACETYLENE GENERATORS 63 

the small openings in the torches causes them to be- 
come partly closed and alters the proportions of the 
gases to the detriment of the welding flame. The only 
remedy for this trouble is to avoid its cause and 
secure cool generation. 

Overheating can be detected by the appearance of 
the sludge remaining after the gas has been made. 
Discoloration, yellow or brown, shows that there has 
been trouble in this direction and the resultant effects 
at the torches may be looked for. The abundance of 
water in the carbide to water machines effects this 
cooling naturally and is a characteristic of well de- 
signed machines of this class. It has been found best 
and has practically become a fundamental rule of 
generation that a gallon of water must be provided 
for each pound of carbide placed in the generator. 
"With this ratio and a generator large enough for 
the number of torches to be supplied, little trouble 
need be looked for with overheating. 

Water to Carbide Generators. — It is, of course, 
much easier to obtain a measured and regular flow of 
water than to obtain such a flow of any solid sub- 
stance, especially when the solid substance is in the 
form of lumps, as is carbide This fact led to the use 
of a great many water-feed generators for all classes 
of work, and this type is still in common use for the 
small portable machines, such, for instance, as those 
used on motor cars for the lamps. The water-feed 
machine is not, however, favored for welding plants, 
as is the carbide feed, in spite of the greater difficul- 
ties attending the handling of the solid material. 

A water-feed generator is made up of the gas pro- 
ducing part and a holder for the acetylene after it 
is made. The carbide is held in a tray formed of a 



64 WELDING 

number of small compartments so that the charge 
in each compartment is nearly equal to that in each 
of the others. The water is allowed to flow into one 
of these compartments in a volume sufficient to pro- 
duce the desired amount of gas and the carbide is 
completely used from this one division. The water 
then floods the first compartment and finally over- 
flows into the next one, where the same process is 
repeated. After using the carbide in this division, 
it is flooded in turn and the water passing on to 
those next in order, uses the entire charge of the 
whole tray. 

These generators are charged with the larger sizes 
of carbide and are easily taken care of. The residue 
is removed in the tray and emptied, making the gen- 
erator ready for a fresh supply of carbide. 

Carbide to Water Generators. — This type also is 
made up of two principal parts, the generating cham- 
ber and a gas holder, the holder being part of the 
generating chamber or a separate device. The gen- 
erator (Figure 10) contains a hopper to receive the 
charge of carbide and is fitted with the feeding mech- 
anism to drop the proper amount of carbide into the 
water as required by the demands of the torches. The 
charge of carbide is of one of the smaller sizes, 
usually "nut" or "quarter." 

Feed Mechanisms. — The device for dropping the 
carbide into the water is the only part of the machine 
that is at all complicated. This complication is 
brought about by the necessity of controlling the 
mass of carbide so that it can never be discharged 
into the water at an excessive rate, feeding it at a 
regular rate and in definite amounts, feeding it posi- 
tively whenever required and shutting off the feed 



ACETYLENE GENERATORS 



65 



just as positively when the supply of gas in the 
holder is enough for the immediate needs. 

The charge of carbide is unavoidably acted upon 
by the water vapor in the generator and will in time 




become more or less pasty and sticky. This is more 
noticeable if the generator stands idle for a consider- 
able length of time This condition imposes another 
duty on the feeding mechanism ; that is, the necessity 
of self-cleaning so that the carbide, no matter in what 



66 WELDING 

condition, cannot prevent the positive action of this 
part of the device, especially so that it cannot prevent 
the supply from being stopped at the proper time. 

The gas holder is usually made in the bell form 
so that the upper portion rises and falls with the 
addition to or withdrawal from the supply of gas 
in the holder. The rise and fall of this bell is often 
used to control the feed mechanism because this 
movement indicates positively whether enough gas 
has been made or that more is required. As the bell 
lowers it sets the feed mechanism in motion, and 
when the gas passing into the holder has raised the 
bell a sufficient distance, the movement causes the 
feed mechanism to stop the fall of carbide into the 
water. In practice, the movement of this part of the 
holder is held within very narrow limits. 

Gas Holders. — No matter how close the adjustment 
of the feeding device, there will always be a slight 
amount of gas made after the fall of carbide is 
stopped, this being caused by the evolution of gas 
from the carbide with which water is already in con- 
tact. This action is called "after generation" and 
the gas holder in any type of generator must provide 
sufficient capacity to accommodate this excess gas. 
As a general rule the water to carbide generator 
requires a larger gas holder than the carbide to water 
type because of the greater amount of carbide being 
acted upon by the water at any one time, also be- 
cause the surface of carbide presented to the moist 
air within the generating chamber is greater with 
this type. 

Freezing. — Because of the rather large body of 
water contained in any type of generator, there is 
always danger of its freezing and rendering the 



ACETYLENE GENERATORS 67 

device inoperative unless placed in a temperature 
above the freezing point of the water. It is, of 
course, dangerous and against the insurance rules to 
place a generator in the same room with a fire of any 
kind, but the room may be heated by steam or hot 
water coils from a furnace in another building or 
in another part of the same building. 

When the generator is housed in a separate struc- 
ture the walls should be made of materials or con- 
struction that prevents the passage of heat or cold 
through them to any great extent. This may be 
accomplished by the use of hollow tile or concrete 
blocks or by any other form of double wall providing 
air spaces between the outer and inner facings. The 
space between the parts of the wall may be filled with 
materials that further retard the loss of heat if this 
is necessary under the conditions prevailing. 

Residue From Generators. — The sludge remaining 
in the carbide to water generator may be drawn off 
into the sewer if the piping is run at a slant great 
enough to give a fall that carries the whole quantity, 
both water and ash, away without allowing settling 
and consequent clogging. Generators are provided 
Avith agitators which are operated to stir the ash up 
with the water so that the whole mass is carried off 
when the drain cock is opened. 

If sewer connections cannot be made in such a way 
that the ash is entirely carried away, it is best to 
run the liquid mass into a settling basin outside of 
the building. This should be in the form of a shallow 
pit which will allow the water to pass off by soaking 
into the ground and by evaporation, leaving the 
comparatively dry ash in the pit. This ash which 
remains is essentially slaked lime and can often be 



68 WELDING 

disposed of to more or less advantage to be used in 
mortar, whitewash, marking paths and any other use 
for which slaked lime is suited. The disposition of 
the ash depends entirely on local conditions. An 
average analysis of this ash is as follows: 

Sand 1.10 per cent. 

Carbon 2.72 " 

Oxide of iron and alumina . . 2.77 

Lime 64.06 

Water and carbonic acid . . . 29.35 

Toaoo 

GENERATOR CONSTRUCTION 

The water for generating purposes is carried in the 
large tank-like compartment directly below the car- 
bide chamber. See Figure 11. This water compart- 
ment is filled through a pipe of such a height that 
the water level cannot be brought above the proper 
point or else the water compartment is provided with 
a drain connection which accomplishes this same re- 
sult by allowing an excess to flow away. 

The quantity of water depends on the capacity of 
the generator inasmuch as there must be one gallon 
for each pound of carbide required. The generator 
should be of sufficient capacity to furnish gas under 
working conditions from one charge of carbide to all 
torches installed for at least five hours continuous 
use. 

After calculating the withdrawal of the whole 
number of torches according to the work they are 
to do for this period of five hours the proper gen- 



ACETYLENE GENERATORS 69 

erator capacity may be found on the basis of one 
cubic foot of gas per hour for each pound of carbide. 
Thus if the torches were to use sixty cubic feet of 
gas per hour, five hours would call for three hundred 
cubic feet and a three hundred pound generator 
should be installed. Generators are rated according 
to their carbide capacity in pounds. 

Charging. — The carbide capacity of the generator 
should be great enough to furnish a continuous sup- 
ply of gas for the maximum operating time, basing 
the quantity of gas generated on four and one-half 
cubic feet from each pound of lump carbide and on 
four cubic feet from each pound of quarter, inter- 
mediate sizes being in proportion. 

Generators are built in such a way that it is impos- 
sible for the acetylene to escape from the gas holding 
compartment during the recharging process. This 
is accomplished (1) by connecting the water inlet 
pipe opening with a shut off valve in such a way 
that the inlet cannot be uncovered or opened without 
first closing the shut off valve with the same move- 
ment of the operator; (2) by incorporating an auto- 
matic or hydraulic one-way valve so that this valve 
closes and acts as a check when the gas attempts to 
flow from the holder back to the generating chamber, 
or by any other means that will positively accomplish 
this result. 

In generators having no separate gas holding 
chamber but carrying the supply in the same com- 
partment in which it is generated, the gas contained 
under pressure is allowed to escape through vent 
pipes into the outside air before recharging with 
carbide. As in the former case, the parts are so 
interlocked that it is impossible to introduce carbide 



70 WELDING 

or water without first allowing the escape of the gas 
in the generator. 

It is required by the insurance rules that the entire 
change of carbide while in the generator be held in 
such a way that it may be entirely removed without 
difficulty in case the necessity should arise. 

Generators should be cleaned and recharged at 
regular stated intervals. This work should be done 
during daylight hours only and likewise all repairs 
should be made at such a time that artificial light 
is not needed. Where it is absolutely necessary to 
use artificial light it should be provided only by 
incandescent electric lamps enclosed in gas tight 
globes. 

In charging generating chambers the old ash and 
all residue must first be cleaned out and the operator 
should be sure that no drain or other pipe has become 
clogged. The generator should then be filled with 
the required amount of water. In charging carbide 
feed machines be careful not to place less than 
a gallon of water in the water compartment for each 
pound of carbide to be used and the water must be 
brought to, but not above, the proper level as indi- 
cated by the mark or the maker's instructions. The 
generating chamber must be filled with the proper 
amount of water before any attempt is made to place 
the carbide in its holder. This rule must always be 
followed. It is also necessary that all automatic water 
seals and valves, as well as any other water tanks, 
be filled with clean water at this time. 

Never recharge with carbide without first cleaning 
the generating chamber and completely refilling with 
clean water. Never test the generator or piping for 
leaks with any flame, and never apply flame to any 



ACETYLENE GENERATORS 71 

open pipe or at any point other than the torch, and 
only to the torch after it has a welding or cutting 
nozzle attached. Never use a lighted match, lamp, 
candle, lantern, cigar or any open flame near a gen- 
erator. Failure to observe these precautions is liable 
to endanger life and property. 

Operation and Care of Generators.— The following 
instructions apply especially to the Davis Bournon- 
ville pressure generator, illustrated in Figure 11. 
The motor feed mechanism is illustrated in Figure 12. 

Before filling the machine, the cover should be 
removed and the hopper taken out and examined to> 
see that the feeding disc revolves freely; that no> 
chains have been displaced or broken, and that the 
carbide displacer itself hangs barely free of the feed- 
ing disc when it is revolved. After replacing the 
cover, replace the bolts and tighten them equally, a 
little at a time all around the circumference of the 
cover — not screwing tight in one place only. Do not 
screw the cover down any more than is necessary to 
make a tight fit. 

To charge the generator, proceed as follows : Open 
the vent valve by turning the handle which extends 
over the filling tube until it stands at a right angle 
with the generator. Open the valve in the water 
filling pipe, and through this fill with water until it 
runs out of the overflow pipe of the drainage cham- 
ber ; then close the valve in the water filling pipe and 
vent valve. Remove the carbide filling plugs and fill 
the hopper with l% // x% r/ carbide ("nut" size). 
Then replace the plugs and the safety-locking lever 
chains. Now rewind the motor weight. Run the 
pressure up to about five pounds by raising the con- 
trolling diaphragm valve lever by hand (Figure 12, 



72 



WELDING 



lever marked E) . Then raise the blow-off lever, 
allowing the gas to blow off until the gauge shows 
about two pounds; this to clear the generator of air 
mixture. Then run the pressure up to about eight 




Figure 11. — Pressure Generator (Davis Bournonville). A, Feed 
motor weight; B, Carbide feed motor; C, Motor control diaphragm; 
D, Carbide hopper ; E, Carbide feed disc ; F, Overflow pipe ; G, Over- 
flow pipe seal ; H, Overflow pipe valve ; J, Filling funnel ; K, Hydraulic 
valve ; L, Expansion chamber ; M, Escape pipe ; N, Feed pipe ; O, 
Agitator for residuum ; P, Residuum valve ; Q, Water level 



ACETYLENE GENERATORS 73 

pounds by raising the controlling valve lever E, or 
until this controlling lever rests against the upper 
wing of the fan governor, and prevents operation 
of the feed motor. After this is done, the motor will 
operate automatically as the gas is consumed. 

Should the pressure rise much above the blow-off 
point, the safety controlling diaphragm valve will 
operate and throw the safety clutch in interference 




Figure 12. — Feed Mechanism of Pressure Generator 

and thus stop the motor. This interference clutch 
will then have to be returned to its former position 
before the motor will operate, but cannot be replaced 
before the pressure has been reduced below the blow- 
off point. 

The parts of the feed mechanism illustrated in 
Figure 12 are as follows : A, motor drum for weight 
cable. B, carbide filling plugs. C, chains for con- 
necting safety locking lever of motor to pins on the 
top of the carbide plugs. D, interference clutch of 
motor. E, lever on feed controlling diaphragm valve. 



74 WELDING 

F, lever of interference controlling diaphragm valve 
that operates interference clutch. G, feed controlling 
diaphragm valve. H, diaphragm valve controlling 
operation of interference clutch. I, interference pin 
to engage emergency clutch. J, main shaft driving 
carbide feeding disc. Y, safety locking lever. 

Recharging Generator. — Turn the agitator handle 
rapidly for several revolutions, and then open the 
residuum valve, having five or six pounds gas pres- 
sure on the machine. If the carbide charge has been 
exhausted and the motor has stopped, there is gen- 
erally enough carbide remaining in the feeding disc 
that can be shaken off, and fed by running the motor 
to obtain some pressure in the generator. The desir- 
ability of discharging the residuum with some gas 
pressure is because the pressure facilitates the dis- 
charge and at the same time keeps the generator full 
of gas, preventing air mixture to a great extent. As 
soon as the pressure is relieved by the withdrawal of 
the residuum, the vent valve should be opened, as if 
the pressure is maintained until all of the residuum 
is discharged gas would escape through the discharge 
valve. 

Having opened the vent pipe valve and relieved 
the pressure, open the valve in the water filling tube. 
Close the residuum valve, then run in several gallons 
of water and revolve the agitator, after which draw 
out the remaining residuum; then again close the 
residuum valve and pour in water until it discharges 
from the overflow pipe of the drainage chamber. It 
is desirable in filling the generator to pour the water 
in rapidly enough to keep the filling pipe full of 
water, so that air will not pass in at the same time. 

After the generator is cleaned and filled with 



ACETYLENE GENERATORS 75 

water, fill with carbide and proceed in the same man- 
ner as when first charging. 

Carbide Feed Mechanism. — Any form of carbide 
to water machine should be so designed that the car- 
bide never falls directly from its holder into the 
water, but so that it must take a more or less cir- 
cuitous path. This should be true, no matter what 
position the mechanism is in. One of the commonest 
types of forced feed machine carries the carbide in 
a hopper with slanting sides, this hopper having a 
large opening in the bottom through which the car- 
bide passes to a revolving circular plate. As the 
pieces of carbide work out toward the edge of the 
plate under the influence of the mass behind them, 
they are thrown off into the water by small stationary 
fins or plows which are in such a position that they 
catch the pieces nearest the edges and force them 
off as the plate revolves. This arrangement, while 
allowing a free passage for the carbide, prevents an 
excess from falling should the machine stop in any 
position. 

When, as is usually the case, the feed mechanism 
is actuated by the rise or fall of pressure in the 
generator or of the level of some part of the gas 
holder, it must be built in such a way that the feed- 
ing remains inoperative as long as the filling opening 
on the carbide holder remains open. 

The feed of carbide should always be shut off and 
controlled so that under no condition can more gas 
be generated than could be cared for by the relief 
valve provided. It is necessary also to have the feed 
mechanism at least ten inches above the surface of 
the water so that the parts will never become clogged 
with damp lime dust. 



76 WELDING 

Motor Feed. — The feed mechanism itself is usually 
operated by power secured from a slowly falling 
weight which, through a cable, revolves a drum. To 
this drum is attached suitable gearing for moving the 
feed parts with sufficient power and in the way 
desired. This part, called the motor, is controlled 
by two levers, one releasing a brake and allowing the 
motor to operate the feed, the other locking the gear- 
ing so that no more carbide will be dropped into the 
water. These levers are moved either by the quantity 
of gas in the holder or by the pressure of the gas, 
depending on the type of machine. 

With a separate gas holder, such as used with low 
pressure systems, the levers are operated by the rise 
and fall of the bell of the holder or gasometer, alter- 
nately starting and stopping the motor as the bell 
falls and rises again. Medium pressure generators are 
provided with a diaphragm to control the feed motor. 

This diaphragm is carried so that the pressure 
within the generator acts on one side while a spring, 
whose tension is under the control of the operator, 
acts on the other side. The diaphragm is connected 
to the brake and locking device on the motor in 
such a way that increasing the tension on the spring 
presses the diaphragm and moves a rod that releases 
the brake and starts the feed. The gas pressure, 
increasing with the continuation of carbide feed, acts 
on the other side and finally overcomes the pressure 
of the spring tension, moving the control rod the 
other way and stopping the motor and carbide feed. 
This spring tension is adjusted and checked with the 
help of a pressure gauge attached to the generating 
chamber. 

Gravity Feed. — This type of feed differs from the 



ACETYLENE GENERATORS 77 

foregoing in that the carbide is simply released and 
is allowed to fall into the water without being forced 
to do so. Any form of valve that is sufficiently 
powerful in action to close with the carbide passing 
through is used and is operated by the power secured 
from the rise and fall of the gas holder bell. When 
this valve is first opened the carbide runs into the 
water until sufficient pressure and volume of gas is 
generated to raise the bell. This movement operates 
the arm attached to the carbide shut off valve and 
slowly closes it. A fall of the bell occasioned by gas 
being withdrawn again opens the valve and more gas 
is generated. 

Mechanical Feed. — The previously described meth- 
ods of feeding carbide to the water have all been 
automatic in action and do not depend on the oper- 
ator for their proper action. 

Some types of large generating plants have a 
power-driven feed, the power usually being from 
some kind of motor other than one operated by a 
weight, such as a water motor, for instance This 
motor is started and stopped by the operator when, 
in his judgment, more gas is wanted or enough has 
been generated. This type of machine, often called 
a "non-automatic generator," is suitable for large 
installations and is attached to a gas holder of suffi- 
cient size to hold a day's supply of acetylene. The 
generator can then be operated until a quantity of 
gas has been made that will fill the large holder, or 
gasometer, and then allowed to remain idle for some 
time. 

Gas Holders. — The commonest type of gas con- 
tainer is that known as a gasometer. This consists 
of a circular tank partly filled with water, into which 



78 WELDING 

is lowered another circular tank, inverted, which is 
made enough smaller in diameter than the first one 
so that three-quarters of an inch is left between them. 
This upper and inverted portion, called the bell, 
receives the gas from the generator and rises or falls 
in the bath of water provided in the lower tank as 
a greater or less amount of gas is contained in it. 

These holders are made large enough so that they 
will provide a means of caring for any after genera- 
tion and so that they maintain a steady and even 
flow. The generator, however, must be of a capacity 
great enough so that the gas holder will not be drawn 
on for part of the supply with all torches in opera- 
tion. That is, the holder must not be depended on 
for a reserve supply. 

The bell of the holder is made so that when full 
of gas its lower edge is still under a depth of at 
least nine inches of water in the lower tank. Any 
further rise beyond this point should always release 
the gas, or at least part of it, to the escape pipe so 
that the gas will under no circumstances be forced 
into the room from between the bell and tank. The 
bell is guided in its rise and fall by vertical rods so 
that it will not wedge at any point in its travel. 

A condensing chamber to receive the water which 
condenses from the acetylene gas in the holder is 
usually placed under this part and is provided with 
a drain so that this water of condensation may be 
easily removed. 

Filtering. — A small chamber containing some 
closely packed but porous material such as felt is 
placed in the pipe leading to the torch lines. As 
the acetylene gas passes through this filter the parti- 
cles of lime dust and other impurities are extracted 



ACETYLENE GENERATORS 79 

from it so that danger of clogging the torch openings 
is avoided as much as possible. 

The gas is also filtered to a large extent by its 
passage through the water in the generating chamber, 
this filtering or "scrubbing" often being facilitated 
by the form of piping through which the gas must 
pass from the generating chamber into the holder. 
If the gas passes out of a number of small openings 
when going into the holder the small bubbles give 
a better washing than large ones would. 

Piping. — Connections from generators to service 
pipes should preferably be made with right and left 
couplings or long thread nipples with lock nuts. If 
unions are used, they should be of a type that does 
not require gaskets. The piping should be carried 
and supported so that any moisture condensing in 
the lines will drain back toward the generator and 
where low points occur they should be drained 
through tees leading into drip cups which are per- 
manently closed with screw caps or plugs. No pet 
cocks should be used for this purpose. 

For the feed pipes to the torch lines the following 
pipe sizes are recommended. 

% inch pipe. 26 feet long. 2 cubic feet per hour. 
y 2 inch pipe. 30 feet long. 4 cubic feet per hour. 
% inch pipe. 50 feet long. 15 cubic feet per hour. 

1 inch pipe. 70 feet long. 27 cubic feet per hour. 

li/4 inch pipe. 100 feet long. 50 cubic feet per hour. 

1 y 2 i ncn pipe. 150 feet long. 65 cubic feet per hour. 

2 inch pipe. 200 feet long. 125 cubic feet per hour. 
2y 2 inch pipe. 300 feet long. 190 cubic feet per hour. 

3 inch pipe. 450 feet long. 335 cubic feet per hour. 
"When drainage is possible into a sewer, the gen- 
erator should not be connected directly into the sewer 



80 WELDING 

but should first discharge into an open receptacle, 
which may in turn be connected to the sewer. 

No valves or pet cocks should open into the gen- 
erator room or any other room when it would be 
possible, by opening them for draining purposes, to 
allow any escape of gas. Any condensation must 
be removed without the use of valves or other work- 
ing parts, being drained into closed receptacles. It 
should be needless to say that all the piping for gas 
must be perfectly tight at every point in its length. 

Safety Devices. — Good generators are built in such 
a way that the operator must follow the proper order 
of operation in charging and cleaning as well as in 
all other necessary care. It has been mentioned that 
the gas pressure is released or shut off before it is 
possible to fill the water compartment, and this same 
idea is carried further in making the generator inop- 
erative and free from gas pressure before opening 
the residue drain of the carbide filling opening on 
top of the hopper. Some machines are made so that 
they automatically cease to generate should there be 
a sudden and abnormal withdrawal of gas such as 
would be caused by a bad leak. This method of 
adding safety by automatic means and interlocking 
parts may be carried to any extent that seems desir- 
able or necessary to the maker. 

All generators should be provided with escape or 
relief pipes of large size which lead to the open air. 
These pipes are carried so that condensation will 
drain back toward the generator and after being led 
out of the building to a point at least twelve feet 
above ground, they end in a protecting hood so that 
no rain or solid matter can find its way into them. 
Any escape of gas which might ordinarily pass into 



ACETYLENE GENERATORS 81 

the generator room is led into these escape pipes, all 
parts of the system being connected with the pipe 
so that the gas will find this way out. 

Safety blow off valves are provided so that any 
excess gas which cannot be contained by the gas 
holder may be allowed to escape without causing an 
undue rise in pressure. This valve also allows the 
escape of pressure above that for which the generator 
was designed. Gas released in this way passes into 
the escape pipe just described. 

Inasmuch as the pressure of the oxygen is much 
greater than that of the acetylene when used in the 
torch, it will be seen that anything that caused the 
torch outlet to become closed would allow the oxygen 
to force the acetylene back into the generator and 
the oxygen would follow it, making a very explosive 
mixture. This return of the gas is prevented by a 
hydraulic safety valve or back pressure valve, as it is 
often called. 

Mechanical check valves have been found unsuit- 
able for this use and those which employ water as a 
seal are now required by the insurance rules. The 
valve itself (Figure 13) consists of a large cylinder 
containing water to a certain depth, which is indi- 
cated on the valve body. Two pipes come into the 
upper end of this cylinder and lead down into the 
water, one being longer than the other. The shorter 
pipe leads to the escape pipe mentioned above, while 
the longer one comes from the generator. The upper 
end of the cylinder has an opening to which is at- 
tached the pipe leading to the torches. 

The gas coming from the generator through the 
longer pipe passes out of the lower end of the pipe 
which is under water and bubbles up through the 



WELDING 




Figure 13. — Hydraulic Back- 
Pressure Valve. A, Acetylene sup- 
ply line ; B, Vent pipe ; 0, Water 
filling plug; D, Acetylene service 
cock; B, Plug to gauge height of 
water ; F, Gas openings under 
water ; G, Return pipe tor sealing 
water ; H, Tube to carry gas be- 
low water line ; /., Tube to carry 
gas to escape pipe ; J, Gas cham- 
ber ; K, Plug in upper gas cham- 
ber ; L, High water level ; M, 
Opening through which water re- 
turns ; O, Bottom clean out cast- 
ing 



ACETYLENE GENERATORS 83 

water to the space in the top of the cylinder. From 
there the gas goes to the pipe leading to the torches. 
The shorter pipe is closed by the depth of water so 
that the gas does not escape to the relief pipe. As 
long as the gas flows in the normal direction as de- 
scribed there will be no escape to the air. Should 
the gas in the torch line return into the hydraulic 
valve its pressure will lower the level of water in the 
cylinder by forcing some of the liquid up into the 
two pipes. As the level of the water lowers, the 
shorter pipe will be uncovered first, and as this is 
the pipe leading to the open air the gas will be 
allowed to escape, while the pipe leading back to the 
generator is still closed by the water seal. As soon 
as this reverse flow ceases, the water will again resume 
its level and the action will continue. Because of 
the small amount of water blown out of the escape 
pipe each time the valve is called upon to perform 
this duty, it is necessary to see that the correct water 
level is always maintained. 

While there are modifications of this construction, 
the same principle is used in all types. The pressure 
escape valve is often attached to this hydraulic valve 
body. 

Construction Details. — Flexible tubing (except at 
torches), swing pipe joints, springs, mechanical check 
valves, chains, pulleys and lead or fusible piping 
should never be used on acetylene apparatus except 
where the failure of those parts will not affect the 
safety of the machine or permit, either directly or 
indirectly, the escape of gas into a room. Floats 
should not be used except where failure will only 
render the machine inoperative. 

It should be said that the National Board of Fire 



84 WELDING 

Underwriters have established an inspection service 
for acetylene generators and any apparatus which 
bears their label, stating that that particular model 
and type has been passed, is safe to use. This service 
is for the best interests of all concerned and looks 
toward the prevention of accidents. Such inspection 
is a very important and desirable feature of any 
outfit and should be insisted upon. 

Location of Generators. — Generators should pref- 
erably be placed outside of insured buildings and 
in properly constructed generator houses. The oper- 
ating mechanism should have ample room to work 
in and there should be room enough for the attendant 
to reach the various parts and perform the required 
duties without hindrance or the need of artificial 
light. They should also be protected from tampering 
by unauthorized persons. 

Generator houses should not be within five feet of 
any opening into, nor have any opening toward, any 
adjacent building, and should be kept under lock and 
key. The size of the house should be no greater than 
called for by the requirements mentioned above and 
it should be well ventilated. 

The foundation for the generator itself should be 
of brick, stone, concrete or iron, if possible. If of 
wood, they should be extra heavy, located in a dry 
place and open to circulation of air. A board plat- 
form is not satisfactory, but the foundation should 
be of heavy planking or timber to make a firm base 
and so that the air can circulate around the wood. 

The generator should stand level and no strain 
should be placed on any of the pipes or connections 
or any parts of the generator proper. 



CHAPTER IV 

WELDING INSTEUMENTS 

VALVES 

Tank Valves. — The acetylene tank valve is of the 
needle type, fitted with suitable stuffing box nuts and 
ending- in an exposed square shank to which the 
special wrench may be fitted when the valve is to be 
opened or closed. 

The valve used on Linde oxygen cylinders is also 
a needle type, but of slightly more complex construc- 
tion. The body of the valve, which screws into the 
top of the cylinder, has an opening below through 
which the gas comes from the cylinder, and another 
opening on the side through which it issues to the 
torch line. A needle screws down from above to 
close this lower opening. The needle which closes 
the valve is not connected directly to the threaded 
member, but fits loosely into it. The threaded part 
is turned by a small hand wheel attached to the upper 
end. "When this hand wheel is turned to the left, or 
up, as far as it will go, opening the valve, a rubber 
disc is compressed inside of the valve body and this 
disc serves to prevent leakage of the gas around the 
spindle. 

The oxygen valve also includes a safety nut having 
a small hole through it closed by a fusible metal 
which melts at 250° Fahrenheit. Melting of this 
plug allows the gas to exert its pressure against a 
thin copper diaphragm, this diaphragm bursting 
under the gas pressure and allowing the oxygen to 
escape into the air. 

85 



WELDING 



The hand wheel and upper end of the valve mech- 
anism are protected during shipment by a large steel 
cap which covers them when screwed on to the end 
of the cylinder. This cap should always be in place 
when tanks are received from the makers or returned 
to them. 



High pressure-* 
Gauge con- 
nection 



CONNECTION 
TO OXYGEN CYLINDER 




Figure 14. — Regulating Valve 

Regulating Valves. — While the pressure in the 
gas containers may be anything from zero to 1,800 
pounds, and will vary as the gas is withdrawn, the 
pressure of the gas admitted to the torch must be 
held steady and at a definite point. This is accom- 
plished by various forms of automatic regulating 
valves, which, while they differ somewhat in details 
of construction, all operate on the same principle. 

The regulator body (Figure 14) carries a union 
which attaches to the side outlet on the oxygen tank 
valve. The gas passes through this union, following 



WELDING INSTRUMENTS 87 

an opening which leads to a large gauge which regis- 
ters the pressure on the oxygen remaining in the tank 
and also to a very small opening in the end of a tube. 
The gas passes through this opening and into the 
interior of the regulator body. Inside of the body 
is a metal or rubber diaphragm placed so that the 
pressure of the incoming gas causes it to bulge 
slightly. Attached to the diaphragm is a sleeve or 
an arm tipped with a small piece of fibre, the fibre 
being placed so that it is directly opposite the small 
hole through which the gas entered the diaphragm 
chamber. The slight movement of the diaphragm 
draws the fibre tightly over the small opening through 
which the gas is entering, with the result that further 
flow is prevented. 

Against the opposite side of the diaphragm is the 
end of a plunger. This plunger is pressed against 
the diaphragm by a coiled spring. The tension on 
the coiled spring is controlled by the operator through 
a threaded spindle ending in a wing or milled nut on 
the outside of the regulator body. Screwing in on 
the nut causes the tension on the spring to increase, 
with a consequent increase of pressure on the side of 
the diaphragm opposite to that on which the gas acts. 
Inasmuch as the gas pressure acted to close the small 
gas opening and the spring pressure acts in the oppo- 
site direction from the gas, it will be seen that the 
spring pressure tends to keep the valve open. 

When the nut is turned way out there is, of course, 
no pressure on the spring side of the diaphragm and 
the first gas coming through automatically closes the 
opening through which it entered. If now the ten- 
sion on the spring be slightly increased, the valve 
will again open and admit gas until the pressure of 



88 WELDINa 

gas within the regulator is just sufficient to overcome 
the spring pressure and again close the opening. 
There will then be a pressure of gas within the regu- 
lator that corresponds to the pressure placed on the 
spring by the operator. An opening leads from the 
regulator interior to the torch lines so that all gas 
going to the torches is drawn from the diaphragm 
chamber. 

Any withdrawal of gas will, of course, lower the 
pressure of that remaining inside the regulator. The 
spring tension, remaining at the point determined by 
the operator, will overcome this lessened pressure of 
the gas, and the valve will again open and admit 
enough more gas to bring the pressure back to the 
starting point. This action continues as long as the 
spring tension remains at this point and as long as 
any gas is taken from the regulator. Increasing the 
spring tension will require a greater gas pressure to 
close the valve and the pressure of that in the regu- 
lator will be correspondingly higher. 

When the regulator is not being used, the hand 
nut should be unscrewed until no tension remains on 
the spring, thus closing the valve. After the oxygen 
tank valve is open, the regulator hand nut is slowly 
screwed in until the spring tension is sufficient to 
give the required pressure in the torch lines. Another 
gauge is attached to the regulator so that it com- 
municates with the interior of the diaphragm cham- 
ber, this gauge showing the gas pressure going to the 
torch. It is customary to incorporate a safety valve 
in the regulator which will blow off at a dangerous 
pressure. 

In regulating valves and tank valves, as well as 
all other parts with which the oxygen comes in con- 



WELDING INSTRUMENTS 



SO 



tact, it is not permissible to use any form of oil or 
grease because of danger of ignition and explosion. 
The mechanism of a regulator is too delicate to be 
handled in the ordinary shop and should any trouble 
or leakage develop in this part of the equipment it 
should be sent to a company familiar with this class 
of work for the necessary repairs. Gas must never 
be admitted to a regulator until the hand nut is all 




Figure 15. — High and Low Pressure Gauges with Regulator 

the way out, because of danger to the regulator itself 
and to the operator as well. A regulator can only be 
properly adjusted when the tank valve and torch 
valves are fully opened. 

Acetylene regulators are used in connection with 
tanks of compressed gas. They are built on exactly 
the same lines as the oxygen regulating valve and 
operate in a similar way. One gauge only, the low 
pressure indicator, is used for acetylene regulators, 
although both high and low pressure may be used 
if desired. (See Figure 15.) 



90 WELDING 



TORCHES 



Flame is always produced by the combustion of 
a gas with oxygen and in no other way. When we 
burn oil or candles or anything else, the material of 
the fuel is first turned to a gas by the heat and is 
then burned by combining with the oxygen of the air. 
If more than a normal supply of air is forced into 
the flame, a greater heat and more active burning 
follows. If the amount of air, and consequently oxy- 
gen, is reduced, the flame becomes smaller and weaker 
and the combustion is less rapid. A flame may be 
easily extinguished by shutting off all of its air 
supply. • 

The oxygen of the combustion only forms one-fifth 
of the total volume of air; therefore, if we were tq 
supply pure oxygen in place of air, and in equal 
volume, the action would be several times as intense. 
If the oxygen is mixed with the fuel gas in the pro- 
portion that burns to the very best advantage, the 
flame is still further strengthened and still more heat 
is developed because of the perfect combustion. The 
greater the amount of fuel gas that can be burned 
in a certain space and within a certain time, the 
more heat will be developed from that fuel. 

The great amount of heat contained in acetylene 
gas, greater than that found in any other gaseous 
fuel, is used by leading this gas to the oxy-acetylene 
torch and there combining it with just the right 
amount of oxygen to make a flame of the greatest 
power and heat than can possibly be produced by any 
form of combustion of fuels of this kind. The heat 
developed by the flame is about 6300° Fahrenheit and 
easily melts all the metals, as well as other solids. 



WELDING INSTRUMENTS 91 

Other gases have been and are now being used in 
the torch. None of them, however, produce the heat 
that acetylene does, and therefore the oxy-acetylene 
process has proved the most useful of all. Hydrogen 
was used for many years before acetylene was intro- 
duced in this field. The oxy-hydrogen flame develops 
a heat far below that of oxy-acetylene, namely 4500° 
Fahrenheit. Coal gas, benzine gas, blaugas and 
others have also been used in successful applications, 
but for the present we will deal exclusively with the 
acetylene fuel. 

It was only with great difficulty that the obstacles 
in the way of successfully using acetylene were over- 
come by the development of practicable ■ controlling 
devices and torches, as well as generators. At pres- 
ent the oxy-acetylene process is the most universally 
adaptable, and probably finds the most widely ex- 
tended field of usefulness of any welding process. 

The theoretical proportion of the gases for perfect 
combustion is two and one-half volumes of oxygen to 
one of acetylene. In practice this proportion is one 
and one-eighth or one and one-quarter volumes of 
oxygen to one volume of acetylene, so that the cost 
is considerably reduced below what it would be if the 
theoretical quantity were really necessary, as oxygen 
costs much more than acetylene in all cases. 

While the heat is so intense as to fuse anything 
brought into the path of the flame, it is localized in 
the small "welding cone" at the torch tip so that 
the torch is not at all difficult to handle without 
special protection except for the eyes, as already 
noted. The art of successful welding may be ac- 
quired by any operator of average intelligence within 
a reasonable time and with some practice. One 



92 WELDING 

trouble met with in the adoption of this process has 
been that the operation looks so simple and so easy 
of performance that unskilled and unprepared per- 
sons have been tempted to try welding, with results 
that often caused condemnation of the process, when 
the real fault lay entirely with the operator. 

The form of torch usually employed is from twelve 
to twenty-four inches long and is composed of a 
handle at one end with tubes leading from this handle 
to the "welding head" or torch proper. At or near 
one end of the handle are adjustable cocks or valves 
for allowing the gases to flow into the torch or to 
prevent them from doing so. These cocks are often 
used for regulating the pressure and amount of gas 
flowing to the welding head, but are not always con- 
structed for this purpose and should not be so used 
when it is possible to secure pressure adjustment at 
the regulators (Figure 16). 

Figure 16 shows three different sizes of torches. 
The number 5 torch is designed especially for jew- 
elers ' work and thin sheet steel welding. It is eleven 
inches in length and weighs nineteen ounces. The 
tips for the number 10 torch are interchangeable with 
the number 5. The number 10 torch is adapted for 
general use on light and medium heavy work. It 
has six tips and its length is sixteen inches, with a 
weight of twenty-three ounces. 

The number 15 torch is designed for heavy work, 
being twenty-five inches in length, permitting the 
operator to stand away from the heat of the metal 
being worked. These heavy tips are in two parts, the 
oxygen check being renewable. 

Figures 17 and 18 show two sizes of another weld- 
ing torch. Still another type is shown in Figure 19 



WELDING INSTRUMENTS 



93 








C =31a 5<rz=ga 



ffiO 



=fflo 






94 



WELDING 



with four interchangeable tips, the function of each 
being as follows: 

No. 1. For heavy castings. 

No. 2. Light castings and heavy sheet metal. 

No. 3. Light sheet metal. 

No. 4. Very light sheet metal and wire. 




4 3 2 t 

Figure 17. — Cox Welding Torch (No. 1) 




9 8 6 

Figure 18. — Cox Welding Torch (No. 2) 




Figure 19. — Monarch Welding Torch 

At the side of the shut off cock away from the torch 
handle the gas tubes end in standard forms of hose 



WELDING INSTRUMENTS 95 

nozzles, to which the rubber hose from the gas supply 
tanks or generators can be attached. The tubes from 
the handle to the head may be entirely separate from 
each other, or one may be contained within the other. 
As a general rule the upper one of two separate tubes 
carries the oxygen, while this gas is carried in the 
inside tube when they are concentric with each other. 

In the welding head is the mixing chamber de- 
signed to produce an intimate mixture of the two 
gases before they issue from the nozzle to the flame. 
The nozzle, or welding tip, of a suitable size and 
design for the work to be handled and the pressure 
of gases being used, is attached to the welding head, 
and consists essentially of the passage at the outer 
end of which the flame appears. 

The torch body and tubes are usually made of 
brass, although copper is sometimes used. The joints 
must be very strong, and are usually threaded and 
soldered with silver solder. The nozzle proper is 
made from copper, because it withstands the heat 
of the flame better than other less suitable metals. 
The torch must be built in such a way that it is not 
at all liable to come apart under the influence of 
high temperatures. 

All torches are constructed in such a way that it 
is impossible for the gases to mix by any possible 
chance before they reach the head, and the amount 
of gas contained in the head and tip after being 
mixed is made as small as possible. In order to 
prevent the return of the flame through the acetylene 
tube under the influence of the high pressure oxygen, 
some form of back flash preventer is usually incor- 
porated in the torch at or near the point at which 
the acetylene enters. This preventer takes the form 



96 



WELDING 



of some porous and heat absorbing material, such 
as aluminum shavings, contained in a small cavity 
through which the gas passes on its way to the head. 
High Pressure Torches. — Torches are divided into 
the same classes as are the generators; that is, high 
pressure, medium pressure and low pressure. As 
mentioned before, the medium pressure is usually 
called the high pressure, because there are very few 
true high pressure systems in use, and comparatively 




Figure 20. — High Pressure Torch Head 



speaking the medium pressure type is one of high 
pressure. 

With a true high pressure torch (Figure 20) the 
gases are used at very nearly equal heads so that the 
mixing before ignition is a simple matter. This type 
admits the oxygen at the inner end of a straight 
passage leading to the tip of the nozzle. The acety- 
lene comes into this same passage from openings at 
one side and near the inner end. The difference in 
direction of the two gases as they enter the passage 
assists in making a homogeneous mixture. The con- 
struction of this nozzle is perfectly simple and is 
easily understood. The true high pressure torch 



WELDING INSTRUMENTS 



97 



nozzle is only suited for use with compressed and 
dissolved acetylene, no other gas being at a sufficient 
pressure to make the action necessary in mixing the 
gases. 

Medium Pressure Torches. — The medium pressure 
(usually called high pressure) torch (Figure 21) 
uses acetylene from a medium pressure generator 
or from tanks of compressed gas, but will not take 
the acetylene from low pressure generators. 




Figure 21. — Medium Pressure Torch Head 



The construction of the mixing chamber and nozzle 
is very similar to that of the high pressure torch, the 
gases entering in the same way and from the same 
positions of openings. The pressure of the acetylene 
is but little lower than that of the oxygen, and the 
two gases, meeting at right angles, form a very inti- 
mate mixture at this point of juncture. The mixture 
in its proportions of gases depends entirely on the 
sizes of the oxygen and acetylene openings into the 
mixing chamber and on the pressures at which the 
gases are admitted. There is a very slight injector 
action as the fast moving stream of oxygen tends to 
draw the acetylene from the side openings into the 



98 WELDING 

chamber, but the operation of the torch does not 
depend on this action to any extent. 

Low Pressure Torches. — The low pressure torch 
(Figure 22) will use gas from low pressure gener- 
ators, from medium pressure machines or from tanks 
in which it has been compressed and dissolved. This 
type depends for a perfect mixture of gas upon the 
principle of the injector just as it is applied in steam 
boiler practice. 




Figure 22. — Low Pressure Torch with Separate Injector Nozzle 



The oxygen enters the head at considerable pres- 
sure and passes through its tube to a small jet within 
the head. The opening of this jet is directly opposite 
the end of the opening through the nozzle which 
forms the mixing chamber and the path of the gases 
to the flame. A small distance. remains between the 
opening from which the oxygen issues and the inner 
opening into the mixing passage. The stream of 
oxygen rushes across this space and enters the mixing 
chamber, being driven by its own pressure. 

The acetylene enters the head in an annular space 
surrounding the oxygen tube. The space between 
oxygen jet and mixing chamber opening is at one 



WELDING INSTRUMENTS 99 

end of this acetylene space and the stream of oxygen 
seizes the acetylene and under the injector action 
draws it into the mixing chamber, it being necessary 
only to have a sufficient supply of acetylene flowing 
into the head to allow the oxygen to draw the re- 
quired proportion for a proper mixture. 

The volume of gas drawn into the mixing chamber 
depends on the size of the injector openings and the 
pressure of the oxygen. In practice the oxygen 
pressure is not altered to produce different sized 
flames, but a new nozzle is substituted which is 
designed to give the required flame. Each nozzle 
carries its own injector, so that the design is always 
suited to the conditions. "While torches are made 
having the injector as a permanent part of the torch 
body, the replaceable nozzle is more commonly used, 
because it makes the one torch suitable for a large 
range of work and a large number of different sized 
flames. With the replaceable head a definite pressure 
of oxygen is required for the size being used, this 
pressure being the one for which the injector and 
corresponding mixing chamber were designed in pro- 
ducing the correct mixture. 

Adjustable Injectors. — Another form of low pres- 
sure torch operates on the injector principle, but the 
injector itself is a permanent part of the torch, the 
nozzle only being changed for different sizes of work 
and flame. The injector is placed in or near the 
handle and its opening is the largest required by any 
work that can be handled by this particular torch. 
The opening through the tip of the injector through 
which the oxygen issues on its way to the mixing 
chamber may be wholly or partly closed by a needle 
valve which may be screwed into the opening or 



100 WELDING 

withdrawn from it, according to the operator's judg- 
ment. The needle valve ends in a milled nnt outside 
the torch handle, this being the adjustment provided 
for the different nozzles. 

Torch Construction. — A well designed torch is so 
designed that the weight distribution is best for hold- 
ing it in the proper position for welding. When a 
torch is grasped by its handle with the gas hose 
attached, it should balance so that it does not feel 
appreciably heavier on one end than on the other. 

The head and nozzle may be placed so that the 
flame issues in a line at right angles with the torch 
body, or they may be attached at an angle convenient 
for the work to be done. The head set at an angle 
of from 120 to 170 degrees with the body is usually 
preferred for general work in welding, while the 
cutting torch usually has its head at right angles 
to the body. 

Removable nozzles have various size openings 
through them and the different sizes are designated 
by numbers from 1 up. The same number does not 
always indicate the same size opening in torches of 
different makes, nor does it indicate a nozzle of the 
same capacity. 

The design of the nozzle, the mixing chamber, the 
injector, when one is used, and the size of the gas 
openings must be such that all these things are suited 
to each other if a proper mixture of gas is to be 
secured. Parts that are not made to work together 
are unsafe if used because of the danger of a flash 
back of the flame into the mixing chamber and gas 
tubes. It is well known that flame travels through 
any inflammable gas at a certain definite rate of 
speed, depending on the degree of inflammability of 



WELDING INSTRUMENTS 101 

the gas. The easier and quicker the gas burns, the 
faster will the flame travel through it. 

If the gas in the nozzle and mixing chamber stood 
still, the flame would immediately travel back into 
these parts and produce an explosion of more or less 
violence. The speed with which the gases issue from 
the nozzle prevent this from happening because the 
flame travels back through the gas at the same speed 
at which the gas issues from the torch tip. Should 
the velocity of the gas be greater than the speed of 
flame propagation through it, it will be impossible 
to keep the flame at the tip, the tendency being for 
a space of unburned gas to appear between tip and 
flame. On the other hand, should the speed of the 
flame exceed the velocity with which the gas comes 
from the torch there will result a flash back and 
explosion. 

Care of Torches. — An oxy-acetylene torch is a very 
delicate and sensitive device, much more so than 
appears on the surface. It must be given equally 
as good care and attention as any other high-priced 
piece of machinery if it is to be maintained in good 
condition for use. 

It requires cleaning of the nozzles at regular inter- 
vals if used regularly. This cleaning is accomplished 
with a piece of copper or brass wire run through the 
opening, and never with any metal such as steel or, 
iron that is harder than the nozzle itself, because of 
the danger of changing the size of the openings. The 
torch head and nozzle can often be cleaned by allow- 
ing the oxygen to blow through at high pressure 
without the use of any tools. 

In using a torch a deposit of carbon will gradually 
form inside of the head, and this deposit will be more 



102 WELDING 

rapid if the operator lights the stream of acetylene 
before turning any oxygen into the torch. This 
deposit may be removed by running kerosene through 
the nozzle while it is removed from the torch, setting 
fire to the kerosene and allowing oxygen to flow 
through while the oil is burning. 

Should a torch become clogged in the head or 
tubes, it may usually be cleaned by removing the 
oxygen hose from the handle end, closing the acety- 
lene cock on the torch, placing the end of the oxygen 
hose over the opening in the nozzle and turning on 
the oxygen under pressure to blow the obstruction 
back through the passage that it has entered. By 
opening the acetylene cock and' closing the oxygen 
cock at the handle, the acetylene passages may then 
be cleaned in the same way. Under no conditions 
should a torch be taken apart any more than to 
remove the changeable nozzle, except in the hands of 
those experienced in this work. 

Nozzle Sizes. — The size of opening through the 
nozzle is determined according to the thickness and 
kind of metal being handled. The following sizes 
are recommended for steel : 







Davis-Bournonville. 


O xw e 1 d L( 


rickness 


of Metal 


{Mi 


jdium Pressure.) 


Pressure 


1/32 






Tip 


No.l 


Head No. 2 


1/16 








2 




5/64 










3 


3/32 








3 


4 


1/8 








4 


5 


3/16 








5 


6 


1/4 








6 


7 


5/16 








7 




3/8 








8 


8 


1/2 








9 


10 


5/8 








10 


12 


3/4 








11 


15 


ery heavy 






12 


15 



WELDING INSTRUMENTS 



103 



Cutting Torches. — Steel may be cut with a jet of 
oxygen at a rate of speed greater than in any other 
practicable way under usual conditions. The action 
consists of burning away a thin section of the metal 
by allowing a stream of oxygen to flow onto it while 
the gas is at high pressure and the metal at a white 
heat. 

The cutting torch (Figure 23) has the same char- 
acteristics as the welding torch, but has an additional 
nozzle or means for temporarily using the welding 



m 




Figure 23. — Cutting Torch 



opening for the high pressure oxygen. The oxj^gen 
issues from the opening while cutting at a pressure 
of from ten to 100 pounds to the square inch. 

The work is first heated to a white heat by adjust- 
ing the torch for a welding flame. As soon as the 
metal reaches this temperature, the high pressure 
oxygen is turned on to the white-hot portion of the 
steel. When the jet of gas strikes the metal it cuts 
straight through, leaving a very narrow slot and 
removing but little metal. Thicknesses of steel up 
to ten inches can be economically handled in this 
way. 

The oxygen nozzle is usually arranged so that it 
is surrounded by a number of small jets for the 
heating flame. It will be seen that this arrangement 



104 



WELDING 



makes the heating flame always precede the oxygen 
jet, no matter in which direction the torch is moved. 

The torch is held firmly, either by hand or with 
the help of special mechanism for gniding it in the 
desired path, and is steadily advanced in the direc- 
tion it is desired to extend the cut, the rate of 
advance being from three inches to two feet per 
minute through metal from nine inches down to one- 
quarter of an inch in thickness. 

The following data on cutting is given by the 
Davis-Bournonville Company : 



w 

o 

m 
m 

a 
x 

o 


p 

<v 
bfl 
>> 
X 
O 

&JD 
P 

P 

o 


CD 

bJD 

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X 

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to 

B 
"5 

CD 

w 


CD 3 
<mCJ 

°<l-t 
+J O 

(V 
CD+J 

J3 CD 

Oft 


<p 

p 

a .2 

>, CD 


U 
CD 
ft 

P 

o 

w 

CD 

CD 
P 


VI 

CD 

CDO 

=1 


1/4 


10 lbs. 


4 lbs. 


.40 


.086 


24 


$ .013 


1/2 


20 


4 


.91 


.150 


15 


.029 


3/4 


30 


4 


1.16 


.150 


15 


.036 


1 


30 


4 


1.45 


.172 


12 


.045 


11/2 


30 


5 


2.40 


.380 


12 


.076 


2 


40 


5 


2.96 


.380 


12 


.093 


4 


50 


5 


9.70 


.800 


7 


.299 


6 


70 


6 


21.09 


1.50 


4 


.648 


9 


100 


6 


43.20 


2.00 


3 


1.311 



Acetylene-Air Torch. — A form of torch which 
burns the acetylene after mixing it with atmospheric 
air at normal pressure rather than with the oxygen 
under higher pressures has been found useful in 
certain pre-heating, brazing and similar operations. 
This torch (Figure 24) is attached by a rubber gas 
hose to any compressed acetylene tank and is regu- 
lated as to flame size and temperature by opening or 
closing the tank valve more or less. 



WELDING INSTRUMENTS 105 

After attaching the torch to the tank, the gas is 
turned on very slowly and is lighted at the torch tip. 
The adjustment should cause the presence of a green- 
ish-white cone of flame surrounded by a larger body 
of burning gas, the cone starting at the mouth of 
the torch. 

By opening the tank ' valve more, a longer and 
hotter name is produced, the length being regulated 




Figure 24. — Acetylene-Air Torch 

by the tank valve also. This torch will give sufficient 
heat to melt steel, although not under conditions 
suited to welding. Because of the excess of acetylene 
always present there is no danger of oxidizing the 
metal being heated. 

The only care required by this torch is to keep the 
small air passages at the nozzle clean and free from 
carbon deposits. The flame should be extinguished 
when not in use rather than turned low, because this 
low flame rapidly deposits large quantities of soot 
in the burner. 



CHAPTER V 

OXY-ACETYLENE WELDING PEACTICE 

PREPARATION OP WORK 

Preheating. — The practice of heating* the metal 
around the weld before applying the torch flame is 
a desirable one for two reasons. First, it makes the 
whole process more economical; second, it avoids the 
danger of breakage through expansion and contrac- 
tion of the work as it is heated and as it cools. 

When it is desired to join two surfaces by welding 
them, it is, of course, necessary to raise the metal 
from the temperature of the surrounding air to its 
melting point, involving an increase in temperature 
of from one thousand to nearly three thousand de- 
grees. To obtain this entire increase of temperature 
with the torch flame is very wasteful of fuel and of 
the operator's time. The total amount of heat nec- 
essary to put into metal is increased by the con- 
ductivity of that metal because the heat applied at 
the weld is carried to other parts of the piece being 
handled until the whole mass is considerably raised 
in temperature. To secure this widely distributed 
increase the various methods of preheating are 
adopted. 

As to the second reason for preliminary heating. 
It is understood that the metal added to the joint is 
molten at the time it flows into place. All the metals 
used in welding contract as they cool and occupy 
a much smaller space than when molten. If addi- 
tional metal is run between two adjoining surfaces 
which are parts of a surrounding body of cool metal, 

106 



OXY-ACETYLENE WELDING PRACTICE 107 

this added metal will cool while the surfaces them- 
selves are held stationary in the position they orig^ 
in ally occupied. The inevitable result is that the 
metal added will crack under the strain, or, if the 
weld is exceptionally strong, the main body of the 
work will be broken by the force of contraction. To 
overcome these difficulties is the second and most 
important reason for preheating and also for slow 
cooling following the completion of the weld. 

There are many ways of securing this preheating. 
The" work may be brought to a red heat in the forge 
if it is cast iron or steel ; it may be heated in special 
ovens built for the purpose; it may be placed in a 
bed of charcoal while suitably supported; it may be 
heated by gas or gasoline preheating torches, and 
with very small work the outer flame of the welding 
torch automatically provides means to this end. 

The temperature of the parts heated should be 
gradually raised in all cases, giving the entire mass 
of metal a chance to expand equally and to adjust, 
itself to the strains imposed by the preheating. After 
the region around the weld has been brought to a 
proper temperature the opening to be filled is ex- 
posed so that the torch flame can reach it, while the 
remaining surfaces are still protected from cold air 
currents and from cooling through natural radiation. 

One of the commonest methods and one of the best 
for handling work of rather large size is to place the 
piece to be welded on a bed of fire brick and build 
a loose wall around it with other fire brick placed in 
rows, one on top of the other, with air spaces left 
between adjacent bricks in each row. The space 
between the brick retaining wall and the work is 
filled with charcoal, which is lighted from below. 



108 WELDLNvi 

The top opening of the temporary oven is then cov- 
ered with asbestos and the fire kept up until the 
work has been uniformly raised in temperature to 
the desired point. 

When much work of the same general character 
and size is to be handled, a permanent oven may be 
constructed of fire brick, leaving a large opening 
through the top and also through one side. Charcoal 
may be used in this form of oven as with the tem- 
porary arrangement, or the heat may be secured 
from any form of burner or torch giving a large 
volume of flame. In any method employing flame to 
do the heating, the work itself must be protected 
from the direct blast of the fire. Baffles of brick or 
metal should be placed between the mouth of the 
torch and the nearest surface of the work so that 
the flame will be deflected to either side and around 
the piece being heated. 

The heat should be applied to bring the point of 
welding to the highest temperature desired and, ex- 
cept in the smallest work, the heat should gradually 
shade off from this point to the other parts of the 
piece. In the case of cast iron and steel the tem- 
perature at the point to be welded should be great 
enough to produce a dull red heat. This will make 
the whole operation much easier, because there will 
be no surrounding cool metal to reduce the tempera- 
ture of the molten material from the welding rod 
below the point at which it will join the work. From 
this red heat the mass of metal should grow cooler 
as the distance from the weld becomes greater, so 
that no great strain is placed upon any one part. 
With work of a very irregular shape it is always 
best to heat the entire piece so that the strains will 



OXY-ACETYLENE WELDING PRACTICE 109 

be so evenly distributed that they can cause no dis- 
tortion or breakage under any conditions. 

The melting point of the work which is being pre- 
heated should be kept in mind and care exercised not 
to approach it too closely. Special care is necessary 
with aluminum in this respect, because of its low 
melting temperature and the sudden weakening and 
flowing without warning. Workmen have carelessly 
overheated aluminum castings and, upon uncovering 
the piece to make the weld, have been astonished to 
find that it had disappeared. Six hundred degrees 
is about the safe limit for this metal. It is possible 
to gauge the exact temperature of the work with a 
pyrometer, but when this instrument cannot be pro- 
cured, it might be well to secure a number of "tem- 
perature cones" from a chemical or laboratory sup- 
ply house. These cones are made from material that 
will soften at a certain heat and in form they are 
long and pointed. Placed in position on the part 
being heated, the point may be watched, and when 
it bends over it is sure that the metal itself has 
reached a temperature considerably in excess of the 
temperature at which that particular cone was de- 
signed to soften. 

The object in preheating the metal around the 
weld is to cause it to expand sufficiently to open the 
crack a distance equal to the contraction when cool- 
ing from the melting point. In the case of a crack 
running from the edge of a piece into the body or 
of a crack wholly within the body, it is usually satis- 
factory to heat the metal at each end of the opening. 
This will cause the whole length of the crack to open 
sufficiently to receive the molten material from the 
rod. 



110 



WELDING 



The judgment of the operator will be called upon 
to decide just where a piece of metal should be heated 
to open the weld properly. It is often possible to 
apply the preheating flame to a point some distance 
from the point of work if the parts are so connected 




Figure 25.- 



-Preheating at A While Welding at B. 
Heated 



C also May Be 



that the expansion of the heated part will serve to 
draw the edges of the weld apart. Whatever part 
of the work is heated to cause expansion and separa- 
tion, this part must remain hot during the entire 
time of welding and must then cool slowly at the 
same time as the metal in the weld cools. 

An example of heating points away from the crack 
might be found in welding a lattice work with one 



OXY-ACETYLENE WELDING PRACTICE 111 

of the bars cracked through (Figure 25). If the 
strips parallel and near to the broken bar are heated 
gradually, the work will be so expanded that the 
edges of the break are drawn apart and the weld 
can be successfully made. In this case, the parallel 
bars next to the broken one would be heated highest, 
the next row not quite so hot and so on for some 
distance away. If only the one row were heated, the 




Figure 26. — Cutting Through the Rim of a Wheel (Cut Shown at A) 

strains set up in the next ones would be sufficient 
to cause a new break to appear. 

If welding is to be done near the central portion 
of a large piece, the strains will be brought to bear 
on the parts farthest away from the center. Should 
a fly wheel spoke be broken and made ready to weld, 
the greatest strain will come on the rim of the wheel. 
In cases like this it is often desirable to cut through 
at the point of greatest strain with a saw or cutting 
torch, allowing free movement while the weld is 
made at the original break (Figure 26). After the 



112 WELDING 

inside weld is completed, the cut may be welded 
without danger, for the reason that it will always 
be at some point at which severe strains cannot be 
set up by the contraction of the cooling metal. 

In materials that will spring to some extent with- 
out breakage, that is, in parts that are not brittle, it 
may be possible to force the work out of shape with 
jacks or wedges (Figure 27) in the same way that 
it would be distorted by heating and expanding some 
portion of it as described. A careful examination 
will show whether this method can be followed in 
such a way as to force the edges of the break to 



W 




Figure 27. — Using a Wedge While Welding 

separate. If the plan seems feasible, the wedges 
may be put in place and allowed to remain while the 
weld is completed. As soon as the work is finished 
the wedges should be removed so that the natural 
contraction can take place without damage. 

It should always be remembered that it is not so 
much the expansion of the work when heated as it 
is the contraction caused by cooling that will do the 
damage. A weld may be made that, to all appear- 
ances, is perfect and it may be perfect when com- 
pleted; but if provision has not been made to allow 
for the contraction that is certain to follow, there 
will be a breakage at some point. It is not possible 
to weld the simplest shapes, other than straight bars, 
without considering this difficulty and making pro- 
vision to take care of it. 



OXY-ACETYLENE WELDING PRACTICE 113 

The exact method to employ in preheating will 
always call for good judgment on the part of the 
workman, and he should remember that the success 
or failure of his work will depend fully as much on 
proper preparation as on correct handling of the 
weld itself. It should be remembered that the outer 
flame of the oxy-acetylene torch may be depended 
on for a certain amount of preheating, as this flame 
gives a very large volume of heat, but a heat that 
is not so intense nor so localized as the welding flame 
itself. The heat of this part of the flame should be 
fully utilized during the operation of melting, the 
metal and it should be so directed, when possible, 
that it will bring the parts next to be joined to as 
high a temperature as possible. 

When the work has been brought to the desired 
temperature, all parts except the break and the sur- 
face immediately surrounding it on both sides should 
be covered with heavy sheet asbestos. This protect- 
ing cover should remain in place throughout the 
operation and should only be moved a distance suffi- 
cient to allow the torch flame to travel in the path 
of the weld. The use of asbestos in this way serves 
a twofold purpose. It retains the heat in the work 
and prevents the breakage that would follow if a 
draught of air were to strike the heated metal, 
and it also prevents such a radiation of heat through 
the surrounding air as would make it almost impos- 
sible for the operator to perform his work, especially 
in the case of large and heavy castings when the 
amount of heat utilized is large. 

Cleaning and Champfering. — A perfect weld can 
never be made unless the surfaces to be joined have 
been properly prepared to receive the new metal. 



114 WELDING 

All spoiled, burned, corroded and rough particles 
must positively be removed with chisel and hammer 
and with a free application of emery cloth and wire 
brush. The metal exposed to the welding flame 
should be perfectly clean and bright all over, or 
else the additional, material will not unite, but will 
only stick at best. 

Following the cleaning it is always necessary to 
bevel, or champfer, the edges except in the thinnest 




Figure 28. — Tapering the Opening Formed by a Break 

sheet metal. To make a weld that will hold, the 
metal must be made into one piece, without holes or 
unfilled portions at any point, and must be solid 
from inside to outside. This can only be accom- 
plished by starting the addition of metal at one 
point and gradually building it up until the outside, 
or top, is reached. With comparatively thin plates 
the molten metal may be started from the side far- 
thest from the operator and brought through, but 
with thicker sections the addition is started in the 
middle and brought flush with one side and then 
with the other. 

It will readily be seen that the molten material 



OXY-ACETYLENE WELDING PRACTICE 115 

cannot be depended upon to flow between the tightly 
closed surfaces of a crack in a way that can be at all 
sure to make a true weld. It will be necessary for 
the operator to reach to the farthest side with the 
flame and welding rod, and to start the new surfaces 
there. To allow this, the edges that are to be joined 
are beveled from one side to the other (Figure 28), 
so that when placed together in approximately the 
position they are to occupy they will Jeave a grooved 
channel between them with its sides at an angle with 

1 \ / _\ 

Figure 29. — Beveling for Thin Work 




Figure 30. — Beveling for Thick Work 

each other sufficient in size to allow access to every 
point of each surface. 

With work less than one-fourth inch thick, this 
angle should be forty-five degrees on each piece 
(Figure 29), so that when they are placed together 
the extreme edges will meet at the bottom of a 
groove whose sides are square, or at right angles, 
to each other. This beveling should be done so that 
only a thin edge is left where the two parts come 
together, just enough points in contact to make the 
alignment easy to hold. "With work of a thickness 
greater than a quarter of an inch, the angle of bevel 
on each piece may be sixty degrees (Figure 30), so 
that when placed together the angle included be- 



116 



WELDING 



tween the sloping sides will also be sixty degrees. 
If the plate is less than one-eighth of an inch thick 
the beveling is not necessary, as the edges may be 
melted all the way through without danger of leaving 
blowholes at any point. 

This beveling may be done in any convenient way. 
A chisel is usually most satisfactory and also quick- 
est. Small sections may be handled by filing, while 
metal that is too hard to cut in either of these wavs 




Figure 31. — Beveling Both Sides of a Thick Piece 







Figure 32. — Beveling the End of a Pipe 

may be shaped on the emery wheel. It is not nec- 
essary that the edges. be perfectly finished and abso- 
lutely smooth, but they should be of regular outline 
and should always taper off to a thin edge so that 
when the flame is first applied it can be seen issuing 
from the far side of the crack. If the work is quite 
thick and is of a shape that will allow it to be turned 
over, the bevel may be brought from both sides 
(Figure 31), so that there will be two grooves, one 
on each surface of the work. After completing the 
weld on one side, the piece is reversed and finished 
on the other side. Figure 32 shows the proper bevel- 



OXY-ACETYLENE WELDING PRACTICE 117 

ing for welding pipe. Figure 33 shows how sheet 
metal may be flanged for welding. 

Welding should not be attempted with the edges 
separated in place of beveled, because it will be 
found impossible to build up a solid web of new 
metal from one side clear through to the other by 
this method. The flame cannot reach the surfaces 
to make them molten while receiving new material 
from the rod, and if the flame does not reach them 
it will only serve to cause a few drops of the metal 
to join and will surely cause a weak and defective 
weld. 

HP 



Figure 33. — Flanging Sheet Metal for Welding 

Supporting Work. — During the operation of weld- 
ing it is necessary that the work be well supported 
in the position it should occupy. This may be done 
with fire brick placed under the pieces in the correct 
position, or, better still, with some form of clamp. 
The edges of the crack should touch each other at 
the point where welding is to start and from there 
should gradually separate at the rate of about one- 
fourth inch to the foot. This is done so that the 
cooling of the molten metal as it is added will draw 
the edges together by its contraction. 

Care must be used to see that the work is sup- 
ported so that it will maintain the same relative 
position between the parts as must be present when 
the work is finished. In this connection it must be 



118 



WELDING 



remembered that the expansion of the metal when 
heated may be great enough to cause serious dis- 
tortion and to provide against this is one of the 
difficulties to be overcome. 

Perfect alignment should be secured between the 
separate parts that are to be joined and the two 
edges must be held up so that they will be in the 
same plane while welding is carried out. If, by any 
chance, one drops below the other while molten metal 






Figure 34. — Rotary Movement of Torch in Welding 



is being added, the whole job may have to be undone 
and done over again. One precaution that is nec- 
essary is that of making sure that the clamping or 
supporting does not in itself pull the work out of 
shape while melted. 

TORCH PRACTICE 

The weld is made by bringing the tip of the weld- 
ing name to the edges of the metals to be joined. 
The torch should be held in the right hand and 
moved slowly along the crack with a rotating motion, 
traveling in small circles (Figure 34), so that the 



OXY-ACETYLENE WELDING PRACTICE 119 

welding flame touches- first on one side of the crack 
and then on the other. On large work the motion 
may be simply back and forth across the crack, 
advancing regularly as the metal unites. It is 
usually best to weld toward the operator rather than 
from him, although this rule is governed by circum- 
stances. The head of the torch should be inclined 
at an angle of about 60 degrees to the surface of the 
work. The torch handle should extend in the same 
line with the break (Figure 35) and not across it, 
except when welding very light plates. 




Figure 35. — Torch Held in Line with the Break 

If the metal is 1/16 inch or less in thickness it is 
only necessary to circle along the crack, the metal 
itself furnishing enough material to complete the 
weld without additions. Heat both sides evenly until 
they flow together. 

Material thicker than the above requires the addi- 
tion of more metal of the same or different kind from 
the welding rod, this rod being held by the left hand. 
The proper size rod for cast iron is one having a 
diameter equal to the thickness of metal being welded 
up to a one-half inch rod, which is the largest used. 
For steel the rod should be one-half the thickness 
of the metal being joined up to one-fourth inch rod. 



120 



WELDING 



As a general rule, better results will be obtained 
by the use of smaller rods, the very small sizes being 
twisted together to furnish enough material while 
retaining the free melting qualities. 

The tip of the rod must at all times be held in 
contact with the pieces being welded and the flame 




Figure 36. — The Welding Rod Should Be Held in the Molten Metal 

must be so directed that the two sides of the crack 
and the end of the rod are melted at the same time 
(Figure 36). Before anything is added from the 
rod, the sides of the crack are melted down suffi- 
ciently to fill the bottom of the groove and join the 



Figure 37. — Welding Pieces of Unequal Thickness 



two sides. Afterward, as metal comes from the rod 
in filling the crack, the flame is circled along the 
joint being made, the rod always following the 
flame. 

Figure 37 illustrates the welding of pieces of 
unequal thickness. 



OXY-ACETYLENE WELDING PRACTICE 121 

Figure 38 illustrates welding at an angle. 

The molten metal may be directed as to where it 
should go by the tip of the welding flame, which has 
considerable force, but care must be taken not to 
blow melted metal on to cooler surfaces which it 
cannot join. If, while welding, a spot appears which, 
does not unite with the weld, it may be handled by 
heating all around it to a white heat and then imme- 
diately welding the bad place. 




Figure 38. — Welding at an Angle 



Never, stop in the middle of a weld, as it is ex- 
tremely difficult to continue smoothly when resuming 
work. 

The Flame. — The welding flame must have exactly 
the right proportions of each gas. If there is too 
much oxygen, the metal will be burned or oxidized; 
the presence of too much acetylene carbonizes the 
metal; that is to say, it adds carbon and makes the 
work harder. Just the right mixture will neither 
burn nor carbonize and is said to be a "neutral" 
flame. The neutral flame, if of the correct size for 
the work, reduces the metal to a melted condition, 
not too fluid, and for a width about the same as the 
thickness of the metal being welded. 

When ready to light the torch, after attaching the 



122 WELDING 

right tip or head as directed in accordance with the 
thickness of metal to be handled, it will be necessary 
to regulate the pressure of gases to secure the neutral 
flame. 

The oxygen will have a pressure of from 2 to 20 
pounds, according to the nozzle used. The acetylene 
will have much less. Even with the compressed gas, 
the pressure should never exceed 10 pounds for the 
largest work, and it will usually be from 4 to 6. 
In low pressure systems, the acetylene will be re- 
ceived at generator pressure. It should first be seen 
that the hand-screws on the regulators are turned 
way out so that the springs are free from any ten- 
sion. It will do no harm if these screws are turned 
back until they come out of the threads. This must 
be done with both oxygen and acetylene regulators. 

Next, open the valve from the generator, or on 
the acetylene tank, and carefully note whether there 
is any odor of escaping gas. Any leakage of this 
gas must be stopped before going on with the work. 

The hand wheel controlling the oxygen cylinder 
valve should now be turned very slowly to the left 
as far as it will go, which opens the valve, and it 
should be borne in mind the pressure that is being 
released. Turn in the hand screw on the oxygen 
regulator until the small pressure gauge shows a 
reading according to the requirements of the noz- 
zle being used. This oxygen regulator adjustment 
should be made with the cock on the torch open, 
and after the regulator is thus adjusted the torch 
cock may be closed. 

Open the acetylene cock on the torch and screw 
in on the acetylene regulator hand-screw until gas 
commences to come through the torch. Light this 



OXY-ACETYLENE WELDING PRACTICE 123 

flow of acetylene and adjust the regulator screw to 
the pressure desired, or, if there is no gauge, so that 
there is a good full flame. With the pressure of 
acetylene controlled by the type of generator it will 
only be necessary to open the torch cock. 

With the acetylene burning, slowly open the oxy- 
gen cock on the torch and allow this gas to join the 
flame. The flame will turn intensely bright and then 
blue white. There will be an outer flame from four 
to eight inches long and from one to three inches 
thick. Inside of this flame will be two more rather 
distinctly defined flames. The inner one at the torch 
tip is very small, and the intermediate one is long 
and pointed. The oxygen should be turned on until 
the two inner flames unite into one blue-white cone 
from one-fourth to one-half inch long and one-eighth 
to one-fourth inch in diameter. If this single, clearly 
defined cone does not appear when the oxygen torch 
cock has been fully opened, turn off some of the 
acetylene until it does appear. 

If too much oxygen is added to the flame, there 
will still be the central blue-white cone, but it will 
be smaller and more or less ragged around the edges 
(Figure 39). When there is just enough oxygen to 
make the single cone, and when, by turning on more 
acetylene or by turning off oxygen, two cones are 
caused to appear, the flame is neutral (Figure 40), 
and the small blue-white cone is called the welding 
flame. 

While welding, test the correctness of the flame 
adjustment occasionally by turning on more acety- 
lene or by turning off some oxygen until two flames 
or cones appear. Then regulate as before to secure 
the single distinct cone. Too much oxygen is not 



124 WELDING 



usually so harmful as too much acetylene, except 
with aluminum. (See Figure 41.) An excessive 
amount of sparks coming from the weld denotes that 




Figure 39. — Oxidizing Flame — Too Much Oxygen 




Figure 40. — Neutral Flame 




Figure 41. — Reducing Flame — Showing an Excess of Acetylene 



OXY-ACETYLENE WELDING PRACTICE 125 

there is too much oxygen in the flame. Should the 
opening in the tip become partly clogged, it will be 
difficult to secure a neutral flame and the tip should 
be cleaned with a brass or copper wire — never with 
iron or steel tools or wire of any kind. While the 
torch is doing its work, the tip may become exces- 
sively hot due to the heat radiated from the molten 
metal. The tip may be cooled by turning off the 
acetylene and dipping in water with a slight flow 
of oxygen through the nozzle to prevent water find- 
ing its way into the mixing chamber. 

The regulators for cutting are similar to those for 
welding, except that higher pressures may be han- 
dled, and they are fitted with gauges reading up to 
200 or 250 pounds pressure. 

In welding metals which conduct the heat very 
rapidly it is necessary to use a much larger nozzle 
and flame than for metals which have not this prop- 
erty. This peculiarity is found to the greatest extent 
in copper, aluminum and brass. 

Should a hole be blown through the work, it may 
be closed by withdrawing the flame for a few sec- 
onds and then commencing to build additional metal 
around the edges, working all the way around and 
finally closing the small opening left at the center 
with a drop or two from the welding rod. 

WELDING VARIOUS METALS 

Because of the varying melting points, rates of 
expansion and contraction, and other peculiarities 
of different metals, it is necessary to give detailed 
consideration to the most important ones. 

Characteristics of Metals. — The welder should thor- 
oughly understand the peculiarities of the various 



126 WELDING 

metals with which he has to deal. The metals and 
their alloys are described under this heading in the 
first chapter of this book and a tabulated list of the 
most important points relating to each metal will 
be found at the end of the present chapter. All this 
information should be noted by the operator of a 
welding installation before commencing actual work. 

Because of the nature of welding, the melting 
point of a metal is of great importance. A metal 
melting at a low temperature should have more care- 
ful treatment to avoid undesired flow than one which 
melts at a temperature which is relatively high. 
When two dissimilar metals are to be joined, the 
one which melts at the higher temperature must be 
acted upon by the flame first and when it is in a 
molten condition the heat contained in it will in 
many cases be sufficient to cause fusion of the lower 
melting metal and allow them to unite without play- 
ing the flame on the lower metal to any great extent. 

The heat conductivity bears a very important 
relation to welding, inasmuch as a metal with a high 
rate of conductance requires more protection from 
cooling air currents and heat radiation than one not 
having this quality to such a marked extent. A 
metal which conducts heat rapidly will require a 
larger volume of flame, a larger nozzle, than other- 
wise, this being necessary to supply the additional 
heat taken away from the welding point by this 
conductance. 

The relative rates of expansion of the various 
metals under heat should be understood in order that 
parts made from such material may have proper 
preparation to compensate for this expansion and 
contraction. Parts made from metals having widely 



OXY-ACETYLENE WELDING PRACTICE 127 

varying rates of expansion must have special treat- 
ment to allow for this quality, otherwise breakage 
is sure to occur. 

Cast Iron. — All spoiled metal should be cut away 
and if the work is more than one-eighth inch in 
thickness the sides of the crack should, be beveled 
to a 45 degree angle, leaving a number of points 
touching at the bottom of the bevel so that the work 
may be joined in its original relation. 

The entire piece should be preheated in a bricked-up 
oven or with charcoal placed on the forge, when size 
does not warrant building a temporary oven. The 
entire piece should be slowly heated and the portion 
immediately surrounding the weld should be brought 
to a dull red. Care should be used that the heat does 
not warp the metal through application to one part 
more than the others. After welding, the work 
should be slowly cooled by covering with ashes, 
slaked lime, asbestos fibre or some other non-con- 
ductor of heat. These precautions are absolutely 
essential in the case of cast iron. 

A neutral flame, from a nozzle proportioned to the 
thickness of the work, should be held with the point 
of the blue-white cone about one-eighth inch from 
the surface of the iron. 

A cast iron rod of correct diameter, usually made 
with an excess of silicon, is used by keeping its end 
in contact with the molten metal and flowing it into 
the puddle formed at the point of fusion. Metal 
should be added so that the weld stands about one- 
eighth inch above the surrounding surface of the 
work. 

Various forms of flux may be used and they are 
applied by dipping the end of the welding rod into 



128 WELDING 

the powder at intervals. These powders may con- 
tain borax or salt, and to prevent a hard, brittle 
weld, graphite or ferro-silicon may be added. Flux 
should be added only after the iron is molten and 
as little as possible should be used. No flux should 
be used just before completion of the work. 

The welding flame should be played on the work 
around the crack and gradually brought to bear on 
the work. The bottom of the bevel should be joined 
first and it will be noted that the cast iron tends to 
run toward the flame, but does not stick together 
easily. A hard and porous weld should be carefully 
guarded against, as described above, and upon com- 
pletion of the work the welded surface should be 
scraped with a file, while still red hot, in order to 
remove the surface scale. 

Malleable Iron. — This material should be beveled 
in the same way that cast iron is handled, and pre- 
heating and slow cooling are equally desirable. The 
flame used is the same as for cast iron and so is the 
flux. The welding rod may be of cast iron, although 
better results are secured with Norway iron wire 
or else a mild steel wire wrapped with a coil of 
copper wire. 

It will be understood that malleable iron turns to 
ordinary cast iron when melted and cooled. "Welds 
in malleable iron are usually far from satisfactory 
and a better joint is secured by brazing the edges 
together with bronze. The edges to be joined are 
brought to a heat just a little below the point at 
which they will flow and the opening is then quickly- 
filled from a rod of Tobin bronze or manganese 
bronze, a brass or bronze flux being used in this 
work. 



OXY-ACETYLENE WELDING PR AC- ICE 129 

Wrought Iron or Semi-Steel. — This metal should 
be beveled and heated in the same way as described 
for cast iron. The flame should be neutral, of the 
same size as for steel, and used with the tip of the 
blue-white cone just touching the work. The welding 
rod should be of mild steel, or, if wrought iron is 
to be welded to steel, a cast iron rod may be used. 
A cast iron flux is well suited for this work. It 
should be noted that wrought iron turns to ordinary 
cast iron if kept heated for any length of time. 

Steel. — Steel should be beveled if more than one- 
eighth inch in thickness. It requires only a local 
preheating around the point to be welded. The 
welding flame should be absolutely neutral, without 
excess of either gas. If the metal is one-sixteenth 
inch or less in thickness, the tip of the blue-white 
cone must be held a short distance from the surface 
of the work; in all other eases the tip of this cone 
is touched to the metal being welded. 

The welding rod may be of mild, low carbon steel 
or of Norway iron. Nickel steel rods may be used 
for parts requiring great strength, but vanadium 
alloys are very difficult to handle. A very satis- 
factory rod is made by twisting together two wires 
of the required material. The rod must be kept 
constantly in contact with the work and should not 
be added until the edges are thoroughly melted. The 
flux may or may not be used. If one is wanted, it 
may be made from three parts iron filings, six parts 
borax and one part sal ammoniac. 

It will be noticed that the steel runs from the 
flame, but tends to hold together. Should foaming 
commence in the molten metal, it shows an excess of 
oxygen and that the metal is being burned. 



130 WKLD1MG 

High carbon steels are very difficult to handle. 
It is claimed that a drop or two of copper added to 
the weld will assist the flow, but will also harden the 
work. An excess of oxygen reduces the amount of 
carbon and softens the steel, while an excess of acety- 
lene increases the proportion of carbon and hardens 
the metal. High speed steels may sometimes be 
welded if first coated with semi-steel before welding. 

Aluminum^ — This is the most difficult of the com- 
monly found metals to weld. This is caused by its 
high rate of expansion and contraction and its lia- 
bility to melt and fall away from under the flame. 
The aluminum seems to melt on the inside first, and, 
without previous warning, a portion of the work will 
simply vanish from in front of the operator's eyes. 
The metal tends to run from the flame and separate 
at the same time. To keep the metal in shape and 
free from oxide, it is worked or puddled while in a 
plastic condition by an iron rod which has been flat- 
tened at one end. Several of these rods should be 
at hand and may be kept in a jar of salt water while 
not being used. These rods must not become coated 
with aluminum and they must not get red hot while 
in the weld. 

The surfaces to be joined, together with the adja- 
cent parts, should be cleaned thoroughly and then 
washed with a 25 per cent solution of nitric acid in 
hot water, used on a swab. The parts should then 
be rinsed in clean water and dried with sawdust. 
It is also well to make temporary fire clay moulds 
back of the parts to be heated, so that the metal 
may be flowed into place and allowed to cool without 
danger of breakage. 

Aluminum must invariably be preheated to about 



OXY-ACETYLENE WELDING PRACTICE 131 

600 degrees, and the whole piece being handled 
should be well covered with sheet asbestos to prevent, 
excessive heat radiation. 

The flame is formed with an excess of acetylene 
such that the second cone extends about an inch, 
or slightly more, beyond the small blue-white point. 
The torch should be held so that the end of this 
second cone is in contact with the work, the small 
cone ordinarily used being kept an inch or an inch 
and a half from the surface of the work. 

"Welding rods of special aluminum are used and 
must be handled with their end submerged in the 
molten metal of the weld at all times. 

When aluminum is melted it forms alumina, an 
oxide of the metal. This alumina surrounds small 
masses of the metal, and as it does not melt at tem- 
peratures below 5000 degrees (while aluminum melts 
at about 1200), it prevents a weld from being made. 
The formation of this oxide is retarded and the oxide 
itself is dissolved by a suitable flux, which usually 
contains phosphorus to break down the alumina. 

Copper. — The whole piece should be preheated and 
kept well covered while welding. The flame must be 
much larger than for the same thickness of steel 
and neutral in character. A slight excess of acety- 
lene would be preferable to an excess of oxygen, and 
in all cases the molten metal should be kept envel- 
oped with the flame. The welding rod is of copper 
which contains phosphorus; and a flux, also contain- 
ing phosphorus, should be spread for about an inch 
each side of the joint. These assist in preventing 
oxidation, which is sure to occur with heated copper. 

Copper breaks very easily at a heat slightly under 



132 WELDING 

the welding temperature and after cooling it is sim- 
ply cast copper in all cases. 

Brass and Bronze. — It is necessary to preheat these 
metals, although not to a very high temperature. 
They must be kept well covered at all times to pre- 
vent undue radiation. The flame should be produced 
with a nozzle one size larger than for the same 
thickness of steel and the small blue-white cone should 
be held from one-fourth to one-half inch above the 
surface of the work. The flame should be neutral 
in character. 

A rod or wire of soft brass containing a large per- 
centage of zinc is suitable for adding to brass, while 
copper requires the use of copper or manganese 
bronze rods. Special flux or borax may be used to 
assist the flow. 

The emission of white smoke indicates that the 
zinc contained in these alloys is being burned away 
and the heat should immediately be turned away or 
reduced. The fumes from brass and bronze welding 
are very poisonous and should not be breathed. 

RESTORATION OF STEEL 

The result of the high heat to which the steel has 
been subjected is that it is weakened and of a dif- 
ferent character than before welding. The operator 
may avoid this as much as possible by first playing 
the outer flame of the torch all over the surfaces 
of the work just completed until these faces are all 
of uniform color, after which the metal should be 
well covered with asbestos and allowed to cool with- 
out being disturbed. If a temporary heating oven 
has been employed, the work and oven should be 
allowed to cool together while protected with the 



OXY-ACETYLENE WELDING PRACTICE 133 

sheet asbestos. If the outside air strikes the freshly 
welded work, even for a moment, the result will be 
breakage. 

A weld in steel will always leave the metal with 
a coarse grain and with all the characteristics of 
rather low grade cast steel. As previously men- 
tioned in another chapter, the larger the grain size 
in steel the weaker the metal will be, and it is the 
purpose of the good workman to avoid, as far as 
possible, this weakening. 

The structure of the metal in one piece of steel 
will differ according to the heat that it has under- 
gone. The parts of the work that have been at the 
melting point will, therefore, have the largest grain 
size and the least strength. Those parts that have 
not suffered any great rise in temperature will be 
practically unaffected, and all the parts between 
these two extremes will be weaker or stronger accord- 
ing to their distance from the weld itself. To restore 
the steel so that it will have the best grain size, the 
operator may resort to either of two methods: (1) 
The grain may be improved by forging. That means 
that the metal added to the weld and the surfaces 
that have been at the welding heat are hammered, 
much as a blacksmith would hammer his finished 
work to give it greater strength. The hammering 
should continue from the time the metal first starts 
to cool until it has reached the temperature at which 
the grain size is best for strength. This temperature 
will vary somewhat with the composition of the metal 
being handled, but in a general way, it may be stated 
that the hammering should continue without inter- 
mission from the time the flame is removed from the 
weld until the steel just begins to show attraction 



134 WELDING 

for a magnet presented to it. This temperature of 
magnetic attraction will always be low enough and 
the hammering should be immediately discontinued 
at this point. (2) A method that is more satisfac- 
tory, although harder to apply, is that of reheating 
the steel to a certain temperature throughout its 
whole mass where the heat has had any effect, and 
then allowing slow and even cooling from this tem- 
perature. The grain size is affected by the tempera- 
ture at which the reheating is stopped and not by 
the cooling, yet the cooling should be slow enough to 
avoid strains caused by uneven contraction. 

After the weld has been completed the steel must 
be allowed to cool until below 1200° Fahrenheit. The 
next step is to heat the work slowly until all those 
parts to be restored have reached a temperature at 
which the magnet just ceases to be attracted. While 
the very best temperature will vary according to the 
nature and hardness of the steel being handled, it 
will be safe to carry the heating to the point indi- 
cated by the magnet in the absence of suitable means 
of measuring accurately these high temperatures. In 
using a magnet for testing, it will be most satisfac- 
tory if it is an electromagnet and not of the perma- 
nent type. The electric current may be secured 
from any small battery and will be the means of 
making sure of the test. The permanent magnet will 
quickly lose its power of attraction under the com- 
bined action of the heat and the jarring to which 
it will be subjected. 

In reheating the work it is necessary to make sure 
that no part reaches a temperature above that desired 
for best grain size and also to see that all parts are 
brought to this temperature. Here enters the great- 



OXY-ACETYLENE WELDING PRACTICE 135 

est difficulty in restoring the metal. The heating 
may be done so slowly that no part of the work on 
the outside reaches too high a temperature and then 
keeps the outside at this heat until the entire mass 
is at the same temperature. A less desirable way 
is to heat the outside higher than this temperature 
and allow the conductivity of the metal to distribute 
the excess to the inside. 

The most satisfactory method, where it can be 
employed, is to make use of a bath of some molten 
metal or some chemical mixture that can be kept 
at the exact heat necessary by means of gas fires 
that admit of close regulation. The temperature of 
these baths may be maintained at a constant point 
by watching a pyrometer, and the finished work may 
be allowed to remain in the bath until all parts have 
reached the desired temperature. 

WELDING INFORMATION 

The following tables include much of the informa- 
tion that the operator must use continually to handle 
the various metals successfully. The temperature 
scales are given for convenience only. The composi- 
tion of various alloys will give an idea of the diffi- 
culties to be contended with by consulting the infor- 
mation on welding various- metals. The remaining 
tables are of self-evident value in this work. 



136 



WELDING 



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OXY-ACETYLENE WELDING PRACTICE 137 
METAL ALLOYS 

(Society of Automobile Engineers) 

Babbitt- 
Tin 84.00% 

Antimony 9.00% 

Copper? 7.00% 

Brass, "White — 

Copper 3.00% to 6.00% 

Tin (minimum) 65.00% 

Zinc 28.00% to 30.00% 

Brass, Red Cast — 

Copper 85.00% 

Tin 5.00% 

Lead 5.00% 

Zinc 5.00% 

Brass, Yellow — 

Copper 62.00% to 65.00% 

Lead 2.00% to 4.00% 

Zinc 36.00% to 31.00% 

Bronze, Hard — 

Copper 87.00% to 88.00% 

Tin 9.50% to 10.50% 

Zinc 1.50% to 2.50% 

Bronze, Phosphor — 

Copper 80.00% 

Tin 10.00% 

Lead 10.00% 

Phosphorus 50% to .25% 

Bronze, Manganese — 

Copper (approximate) , 60.00% 

Zinc (approximate) 40.00% 

Manganese (variable) small 

Bronze, Gear — 

Copper 88.00% to 89.00% 

Tin 11.00% to 12.00% 

Phosphorus 15% to .30% 



138 WELDING 

Aluminum Alloys — 

Aluminum Copper Zinc Manganese 
No. 1.. 90.00% 8.5-7.0% 

No. 2.. 80.00% 2.0-3.0% 15% Not over 0.40% 
No. 3.. 65.00% 35.0% 

Cast Iron — 

Gray Iron Malleable 

Total carbon 3.0 to 3.5% 

Combined carbon ...0.4 to 0.7% 

Manganese 0.4 to 0.7% 0.3 to 0.7 % 

Phosphorus 0.6 to 1.0% Not over 0.2% 

Sulphur Not over 0.1% Not over 0.6% 

Silicon 1.75 to 2.25% Not over 1.0% 

Carbon Steel (10 Point) — 

Carbon 05% to .15% 

Manganese 30% to .60% 

Phosphorus (maximum) .045% 

Sulphur (maximum) .05% 

(20 Point) — 

Carbon 15% to .25% 

Manganese .77 30% to .60% 

Phosphorus (maximum) .045% 

Sulphur (maximum) .05% 

(35 Point) — 

Manganese 50% to .80% 

Carbon 30% to .40% 

Phosphorus (maximum) .05% 

Sulphur (maximum) .05% 

(95 Point) — 

Carbon 90% to 1.05% 

Manganese 25% to .50% 

Phosphorus (maximum) .04% 

Sulphur (maximum) .05% 



OXY-ACETYLENE WELDING PRACTICE 139 

HEATING POWER OF FUEL GASES 

(In B. T. U. per Cubic Foot.) 

Acetylene 1498.99 Ethylene 1562.95 

Hydrogen 291.96 Methane 953.62 

Alcohol 1501.76 

MELTING POINTS OF METALS 

Platinum 3200° 

Iron, wrought 2900° 

malleable 2500° 

cast 2400° 

pure 2760° 

Steel, mild 2700° 

medium 2600° 

hard 2500° 

Copper 1950° 

Brass 1800° 

Silver 1750° 

Bronze 1700° 

Aluminum 1175° 

Antimony 1150° 

Zinc 800° 

Lead 620° 

Babbitt 500-700° 

Solder 500-575° 

Tin 450° 

Note. — These melting points are for average com- 
positions and conditions. The exact proportion of 
elements entering into the metals affects their melting 
points one way or the other in practice. 



140 WELDING 

TENSILE STRENGTH OF METALS 

Alloy steels can be made with tensile strengths as 
high as 300,000 pounds per square inch. Some car- 
bon steels are given below according to "points 1 



, ' ' 



Pounds per Square Inch 

Steel, 10 point 50,000 to 65,000 

20 point 60,000 to 80,000 

40 point 70,000 to 100,000 

60 point 90,000 to 120,000 

Iron, Cast 13,000 to 30,000 

"Wrought 40,000 to 60,000 

Malleable 25,000 to 45,000 

Copper 24,000 to 50,000 

Bronze 30,000 to 60,000 

Brass, Cast 12,000 to 18,000 

Rolled 30,000 to 40,000 

Wire 60,000 to 75,000 

Aluminum 12,000 to 23,000 

Zinc 5,000 to 15,000 

Tin 3,000 to 5,000 

Lead 1,500 to 2,500 

CONDUCTIVITY OF METALS 

(Based on the Value of Silver as 100) 

Heat Electricity- 
Silver 100 100 

Copper 74 99 

Aluminum 38 63 

Brass 23 22 

Zinc 19 29 

Tin 14 15 



OXY-ACETYLENE WELDING PRACTICE 141 

Heat Electricity 

Wrought Iron 12 16 

Steel 11.5 12 • 

Cast Iron 11 12 

Bronze 9 7 

Lead , 8 9 

WEIGHT OF METALS 

(Per Cubic Inch) 



Pounds 



Pounds 



Lead 410 Wrought Iron 278 

Copper' 320 Tin 263 

Bronze 313 Cast Iron 260 

Brass 300 Zinc 258 

Steel 283 Aluminum 093 



EXPANSION OF METALS 



(Measured in Thousandths of an Inch per Foot of 

Length When Raised 1000 Degrees 

in Temperature) 



Inch 

Lead 188 

Zinc 168 

Aluminum 148 

Silver 129 

Bronze 118 



Inch 

Brass 115 

Copper 106 

Steel 083 

Wrought Iron 078 

Cast Iron 068 



CHAPTER VI 
ELECTEIC WELDING 
RESISTANCE METHOD 

Two distinct forms of electric welding apparatus 
are in use, one producing heat by the resistance of the 
metal being treated to the passage of electric cur- 
rent, the other using the heat of the electric arc. 

The resistance process is of the greatest use in 
manufacturing lines where there is a large quantity 
of one kind of work to do, many thousand pieces of 
one kind, for instance. The arc method may be ap- 
plied in practically any case where any other form 
of weld may be made. The resistance process will be 
described first. 

It is a well known fact that a poor conductor of 
electricity will offer so much resistance to the flow of 
electricity that it will heat. Copper is a good con- 
ductor, and a bar of iron, a comparatively poor con- 
ductor, when placed between heavy copper conductors 
of a welder, becomes heated in attempting to carry the 
large volume of current. The degree of heat depends 
on the amount of current and the resistance of the 
conductor. 

In an electric circuit the ends of two pieces of 
metal brought together form the point of greatest 
resistance in the electric circuit, and the abutting 
ends instantly begin to heat. The hotter this metal 
becomes, the greater the resistance to the flow of cur- 
rent; consequently, as the edges of the abutting ends 
heat, the current is forced into the adjacent cooler 

142 



ELECTRIC WELDING 



143 



parts, until there is a uniform heat throughout the 
entire mass. The heat is first developed in the inte- 
rior of the metal so that it is welded there as perfectly 
as at the surface. 




Figure 42. — Spot Welding Machine 



The electric welder (Figure 42) is built to hold the 
parts to be joined between two heavy copper dies or 
contacts. A current of three to five volts, but of 
very great volume (amperage), is allowed to pass 
across these dies, and in going through the metal to 
be welded, heats the edges to a welding temperature. 
It may be explained that the voltage of an electric 



144 WELDING 

current measures the pressure or force with which it 
is being sent through the circuit and has nothing to 
do with the quantity or volume passing. Amperes 
measure the rate at which the current is passing 
through the circuit and consequently give a measure 
of the quantity which passes in any given time. Volts 
correspond to water pressure measured by pounds to 
the square inch ; amperes represent the flow in gallons 
per minute. The low voltage used avoids all danger 
to the operator, this pressure not being sufficient to 
be felt even with the hands resting on the copper 
contacts. 

Current is supplied to the welding machine at a 
higher voltage and lower amperage than is actually 
used between the dies, the low voltage and high am- 
perage being produced by a transformer incorporated 
in the machine itself. By means of windings of suit- 
able size wire, the outside current may be received at 
voltages ranging from 110 to 550 and converted to the 
low pressure needed. 

The source of current for the resistance welder 
must be alternating, that is, the current must first be 
negative in value and then positive, passing from one 
extreme to the other at rates varying from 25 to 133 
times a second. This form is known as alternating 
current, as opposed to direct current, in which there 
is no changing of positive and negative. 

The current must also be what is known as single 
phase, that is, a current which rises from zero in value 
to the highest point as a positive current and then 
recedes to zero before rising to the highest point of 
negative value. Two-phase of three-phase currents 
would give two or three positive impulses during this 
time. 



ELECTRIC WELDING 145 

As long as the current is single phase alternating, 
the voltage and cycles (number of alternations per 
second) may be anything convenient. Various volt- 
ages and cycles are taken care of by specifying all 
these points when designing the transformer which 
is to handle the current. 

Direct current is not used because there is no way 
of reducing the voltage conveniently without placing 
resistance wires in the circuit and this uses power 
without producing useful work. Direct current may 
be changed to alternating by having a direct current 
motor running an alternating current dynamo, or 
the change may be made by a rotary converter, al- 
though this last method is not so satisfactory as the 
first. 

The voltage used in welding being so low to start 
with, it is absolutely necessary that it be maintained 
at the correct point. If the source of current supply 
is not of ample capacity for the welder being used, it 
will be very hard to avoid a fall of voltage when the 
current is forced to pass through the high resistance 
of the weld. The current voltage for various work is 
calculated accurately, and the efficiency of the outfit 
depends to a great extent on the voltage being con- 
stant. 

A simple test for fall of voltage is made by con- 
necting an incandescent electric lamp across the sup- 
ply lines at some point near the welder. The lamp 
should burn with the same brilliancy when the weld is 
being made as at any other time. If the lamp burns 
dim at any time, it indicates a drop in voltage, and 
this condition should be corrected. 

The dynamo furnishing the alternating current 
may be in the same building with the welder and 



146 WELDING 

operated from a direct current motor, as mentioned 
above, or operated from any convenient shafting or 
source of power. When the dynamo is a part of the 
welding plant it should be placed as close to the 
welding machine as possible, because the length of 
the wire used affects the voltage appreciably. 

In order to hold the voltage constant, the Toledo 
Electric Welder Company has devised connections 
which include a rheostat to insert a variable resist- 
ance in the field windings of the dynamo so that the 
voltage may be increased by cutting this resistance 
out at the proper time. An auxiliary switch is con- 
nected to the welder switch so that both switches act 
together. When the welder switch is closed in mak- 
ing a weld, that portion of the rheostat resistance 
between two arms determining the voltage is short 
circuited. This lowers the resistance and the field 
magnets of the dynamo are made stronger so that 
additional voltage is provided to care for the re- 
sistance in the metal being heated. 

A typical machine is shown in the accompanying 
cut (Figure 43). On top of the welder are two jaws 
for holding the ends of the pieces to be welded. The 
lower part of the jaws is rigid while the top is 
brought doAvn on top of the work, acting as a clamp. 
These jaws carry the copper dies through which the 
current enters the work being handled. After the 
work is clamped between the jaws, the upper set 
is forced closer to the lower set by a long com- 
pression lever. The current being turned on with 
the surfaces of the work in contact, they immedi- 
ately heat to the welding point when added pressure 
on the lever forces them together and completes the 
weld. 



ELECTRIC WELDING 



147 




148 



WELDING 



The transformer is carried in the base of the ma- 
chine and on the left-hand side is a regulator for 
controlling' the voltage for various kinds of work. The 
clamps are applied by treadles convenient to the foot 




Figure 43a. — Method of Testing Electric Welder 

of the operator. A treadle is provided which instantly 
releases both jaws upon the completion of the weld. 




Figure 44. — Detail of Water-Cooled Spot Welding Head 



One or both of the copper dies may be cooled by a 
stream of water circulating through it from the city 
water mains (Figure 44). The regulator and switch 
give the operator control of the heat, anything from 



ELECTRIC WELDING 149 

a dull red to the melting point being easily obtained 
by movement of the lever (Figure 45). 

Welding. — It is not necessary to give the metal 
to be welded any special preparation, although when 
very rusty or covered with scale, the rust and scale 




Figure 45. — Welding Head of a Water-Cooled Welder 

should be removed sufficiently to allow good contact 
of clean metal on the copper dies. The cleaner and 
better the stock, the less current it takes, and there 
is less wear on the dies. The dies should be kept 
firm and tight in their holders to make a good contact. 
All bolts and nuts fastening the electrical contacts 
should be clean and tight at all times. 



150 WELDING 

The scale may be removed from forgings by im- 
mersing them in a pickling solution in a wood, stone 
or lead-lined tank. 

The solution is made with five gallons of commer- 
cial sulphuric acid in 150 gallons of water. To get 
the quickest and best results from this method, the 
solution should be kept as near the boiling point as 
possible by having a coil of extra heavy lead pipe 
running inside the tank and carrying live steam. A 
very few minutes in this bath will remove the scale 
and the parts should then be washed in running 
water. After this washing they should be dipped into 
a bath of 50 pounds of unslaked lime in 150 gallons 
of water to neutralize any trace of acid. 

Cast iron cannot be commercially welded, as it is 
high in carbon and silicon, and passes suddenly from 
a crystalline to a fluid state when brought to the weld- 
ing temperature. "With steel or wrought iron the 
temperature must be kept below the melting point to 
avoid injury to the metal. The metal must be heated 
quickly and pressed together with sufficient force to 
push all burnt metal out of the joint. 

High carbon steel can be welded, but must be an- 
nealed after welding to overcome the strains set up 
by the heat being applied at one place. Good results 
are hard to obtain when the carbon runs as high as 
75 points, and steel of this class can only be handled 
by an experienced operator. If the steel is below 25 
points in carbon content, good welds will always be 
the result. To weld high carbon to low carbon steel, 
the stock should be clamped in the dies with the low 
carbon stock sticking considerably further out from 
the die than the high carbon stock. Nickel steel welds 
readily, the nickel increasing the strength of the weld. 



ELECTRIC WELDING 151 

Iron and copper may be welded together by reduc- 
ing the size of the copper end where it comes in con- 
tact with the iron. When welding copper and brass 
the pressure must be less than when welding iron. 
The metal is allowed to actually fuse or melt at the 
juncture and the pressure must be sufficient to force 
the burned metal out. The current is cut off the 
instant the metal ends begin to soften, this being 
done by means of an automatic switch which opens 
when the softening of the metal allows the ends to 
come together. The pressure is applied to the weld 
by having the sliding jaw moved by a weight on the 
end of an arm. 

Copper and brass require a larger volume of cur- 
rent at a lower voltage than for steel and iron. The 
die faces are set apart three times the diameter of» 
the stock for brass and four times the diameter for 
copper. 

Light gauges of sheet steel can be welded to heavy 
gauges or to solid bars of steel by "spot" welding, 
which will be described later. Galvanized iron can 
be welded, but the zinc coating will be burned off. 
Sheet steel can be welded to cast iron, but will pull 
apart, tearing out particles of the iron. 

Sheet copper and sheet brass may be welded, al- 
though this work requires more experience than with 
iron and steel. Some grades of sheet aluminum can 
be spot- welded if the slight roughness left on the sur- 
face under the die is not objectionable. 

Butt Welding. — This is the process which joins the 
ends of two pieces of metal as described in the fore- 
going part of this chapter. The ends are in plain 
sight of the operator at all times and it can easily be 
seen when the metal reaches the welding heat and 



152 WELDING 



begins to soften (Figure 46). It is at this point 
that the pressure must be applied with the lever and 
the ends forced together in the weld. 

The parts are placed in the clamping jaws (Figure 
47) with y 8 to % inch of metal extending beyond the 




Figure 46. — Butt Welder 

jaw. The ends of the metal touch each other and 
the current is turned on by means of a switch. To 
raise the ends to the proper heat requires from 3 
seconds for ^-inch rods to 35 seconds for a l^-inch 
bar. 

This method is applicable to metals having prac- 
tically the same area of metal to be brought into con- 
tact on each end. When such parts are forced to- 



ELECTRIC WELDING 



153 



gether a slight projection will be left in the form 
of a fin or an enlarged portion called an upset. The 
degree of heat required for any work is found by 
moving the handle of the regulator one way or the 
other while testing several parts. When this setting 




Figure 47. — Clamping Dies of a Butt Welder 



is right the work can continue as long as the same 
sizes are being handled. 

Copper, brass, tool steel and all other metals that 
are harmed by high temperatures must be heated 
quickly and pressed together with sufficient force to 
force all burned metal from the weld. 

In case it is desired to make a weld in the form 
of a capital letter T, it is necessary to heat the part 
corresponding to the top bar of the T to a bright red, 
then bring the lower bar to the pre-heated one and 



154 WELDING 

again turn on the current, when a weld can be 
quickly made. 

Spot Welding. — This is a method of joining metal 
sheets together at any desired point by a welded spot 
about the size of a rivet. It is done on a spot welder 
by fusing the metal at the point desired and at the 
same instant applying sufficient pressure to force the 
particles of molten metal together. The dies are usu- 
ally placed one above the other so that the work may 
rest on the lower one while the upper one is brought 
down on top of the upper sheet to be welded. 

One of the dies is usually pointed slightly, the op- 
posing one being left flat. The pointed die leaves a 
slight indentation on one side of the metal, while the 
other side is left smooth. The dies may be reversed 
so that the outside surface of any work may be left 
smooth. The current is allowed to flow through the 
dies by a switch which is closed after pressure is 
applied to the work. 

There is a limit to the thickness of sheet metal that 
can be welded by this process because of the fact 
that the copper rods can only carry a certain quantity 
of current without becoming unduly heated them- 
selves. Another reason is that it is difficult to make 
heavy- sections of metal touch at the welding point 
without excessive pressure. 

Lap welding is the process used when two pieces of 
metal are caused to overlap and when brought to a 
welding heat are forced together by passing through 
rollers, or under a press, thus leaving the welded joint 
practically the same thickness as the balance of the 
work. 

Where it is desirable to make a continuous seam, a 
special machine is required, or an attachment for 



ELECTRIC WELDING 155 

one of the other types. In this form of work the 
stock must be thoroughly cleaned and is then passed 
between copper rollers which act in the same capacity 
as the copper dies. 

Other Applications. — Hardening and tempering can 
be done by clamping the work in the welding dies and 
setting the control and time to bring the metal to the 
proper color, when it is cooled in the usual manner. 

Brazing is done by clamping the work in the jaws 
and heating until the flux, then the spelter has melted 
and run into the joint. Riveting and heading of 
rivets can be done by bringing the dies down on oppo- 
site ends of the rivet after it has been inserted in 
the hole, the dies being shaped to form the heads 
properly. 

Hardened steel may be softened and annealed so 
that it can be machined by connecting the dies of 
the welder to each side of the point to be softened. 
The current is then applied until the work has 
reached a point at which it will soften when cooled. 

Troubles and Remedies. — The following methods 
have been furnished by the Toledo Electric "Welder 
Company and are recommended for this class of work 
whenever necessary. 

To locate grounds in the primary or high voltage 
side of the circuit, connect incandescent lamps in 
series by means of a long piece of lamp cord, as shown, 
in Figure 43a. For 110 volts use one lamp, for 
220 volts use two lamps and for 440 volts use four 
lamps. Attach one end of the lamp cord to one side 
of the switch, and close the switch. Take the other 
end of the cord in the hand and press it against 
some part of the welder frame where the metal is 
clean and bright. Paint, grease and dirt act as in- 



156 WELDING 

sulators and prevent electrical contact. If the lamp 
lights, the circuit is in electrical contact with the 
frame; in other words, grounded. If the lamps do 
not light, connect the wire to a terminal block, die or 
slide. If the lamps then light, the circuit, coils or 
leads are in electrical contact with the large coil in 
the transformer or its connections. 

If, however, the lamps do not light in either case, 
the lamp cord should be disconnected from the switch 
and connected to the other side, and the operations 
of connecting to welder frame, dies, terminal blocks, 
etc., as explained above, should be repeated. If the 
lamps light at any of these connections, a "ground" 
is indicated. "Grounds" can usually be found by 
carefully tracing the primary circuit until a place 
is found where the insulation is defective. Reinsulate 
and make the above tests again to make sure every- 
thing is clear. If the ground can not be located by 
observation, the various parts of the primary circuit 
should be disconnected, and the transformer, switch, 
regulator, etc., tested separately. 

To locate a ground in the regulator or other part, 
disconnect the lines running to the welder from the 
switch. The test lamps used in the previous tests are 
connected, one end of lamp cord to the switch, the 
other end to a binding post of the regulator. Connect 
the other side of the switch to some part of the regu- 
lator housing. (This must be a clean connection to 
a bolt head or the paint should be scraped off.) Close 
the switch. If the lamps light, the regulator winding 
or some part of the switch is "grounded" to the iron 
base or core of the regulator. If the lamps do not 
light, this part of the apparatus is clear. 

This test can be easily applied to any part of the 



ELECTRIC WELDING 157 

welder outfit by connecting to the current carrying 
part of the apparatus, and to the iron base or frame 
that should not carry current. If the lamps light, it 
indicates that the insulation is broken down or is 
defective. 

An A. C. voltmeter can, of course, be substituted 
for the lamps, or a D. C. voltmeter with D. C. cur- 
rent can be used in making the tests. 

A short circuit in the primary is caused by the in- 
sulation of the coils becoming defective and allow- 
ing the bare copper wires to touch each other. This 
may result in a "burn out" of one or more of the 
transformer coils, if the trouble is in the transformer, 
or in the continued blowing of fuses in the line. Feel 
of each coil separately. If a short circuit exists in a 
coil it will heat excessively. Examine all the wires; 
the insulation may have worn through and two of 
them may cross, or be in contact with the frame or 
other part of the welder. A short circuit in the regu- 
lator winding is indicated by failure of the apparatus 
to regulate properly, and sometimes, though not al- 
ways, by the heating of the regulator coils. 

The remedy for a short circuit is to reinsulate the 
defective parts. It is a good plan to prevent trouble 
by examining the wiring occasionally and see that the 
insulation is perfect. 

To Locate Grounds and Short Circuits in the 
Secondary, or Low Voltage Side. — Trouble of this 
kind is indicated by the machine acting sluggish or, 
perhaps, refusing to operate. To make a test, it will 
be necessary to first ascertain the exciting current of 
v>our particular transformer. This is the current the 
transformer draws on "open circuit," or when sup- 
plied with current from the line with no stock in 



158 WELDING 



the welder dies. The following table will give this 
information close enough for all practical purposes: 



K.W. 




Amperes at 




Rating 


110 Volts 


220 Volts 


440 Volts 


550 Volts 


3 


1.5 


.75 


.38 


.3 


5 


2.5 


1.25 


.63 


.5 


8 


3.6 


1.8 


.9 


.72 


10 


4.25 


2.13 


1.07 


.85 


15 


6. 


3. 


1.5 


1.2 


20 


7. 


3.5 


1.75 


1.4 


30 


9. 


4.5 


2.25 


1.8 


35 


9.6 


4.8 


2.4 


1.92 


50 


10. 


5. 


2.5 


2. 



Remove the fuses from the wall switch and substi- 
tute fuses just large enough to carry the "exciting*' 
current. If no suitable fuses are at hand, fine strands 
of copper from an ordinary lamp cord may be used. 
These strands are usually No. 30 gauge wire and will 
fuse at about 10 amperes. One or more strands 
should be used, depending on the amount of exciting 
current, and are connected across the fuse clips in 
place of fuse wire. Place a piece of wood or fibre 
between the welding dies in the welder as though 
you were going to weld them. See that the regulator 
is on the highest point and close the welder switch. 
If the secondary circuit is badly grounded, current 
will flow through the ground, and the small fuses or 
small strands of wire will burn out. This is an' indi- 
cation that both sides of the secondary circuit are 
grounded or that a short circuit exists in a primary 
coil. In either case the welder should not be oper- 
ated until the trouble is found and removed. If, 
however, the small fuses do not * ' blow, ' ' remove same 



ELECTRIC WELDING 159 

and replace the large fuses, then disconnect wires 
running from the wall switch to the wilder and sub- 
stitute two pieces of No. 8 or No. 6 insulated copper 
wire, after scraping off the insulation for an inch or 
two at each end. Connect one wire from the switch to 
the frame of welder; this will leave one loose end. 
Hold this a foot or so away from the place where 
the insulation is cut off ; then turn on the current and 
strike the free end of this wire lightly against one of 
the copper dies, drawing it away quickly. If no 
sparking is produced, the secondary circuit is free 
from ground, and you will then look for a broken 
connection in the circuit. Some caution must be 
used in making the above test, as in case one terminal 
is heavily grounded the testing wire may be fused if 
allowed to stay in contact with the die. 

The Remedy. — 'Clean the slides, dies and terminal 
blocks thoroughly and dry out the fibre insulation if 
it is damp. See that no scale or metal has worked 
under the sliding parts, and that the secondary leads 
do not touch the frame. If the ground is very heavy 
it may be necessary to remove the slides in order to 
facilitate the examination and removal of the ground. 
Insulation, where torn or worn through, must be care- 
fully replaced or taped. If the transformer coils are 
grounded to the iron core of the transformer or to 
the secondary, it may be necessary to remove the coils 
and reinsulate them at the points of contact. A short 
circuited coil will heat excessively and eventually 
burn out. This may mean a new coil if you are unable 
to repair the old one. In all cases the transformer 
windings should be protected from mechanical injury 
or dampness. Unless excessively overloaded, trans- 
formers will last for years without giving a moment 's 



160 WELDING 

trouble, if they are not exposed to moisture or are 
not injured mechanically. 

The most common trouble arises from poor electrical 
contacts, and they are the cause of endless trouble and 
annoyance. See that all connections are clean and 
bright. Take out the dies every day or two and see 
that there is no scale, grease or dirt between them 
and the holders. Clean them thoroughly before re- 
placing. Tighten the bolts running from the trans- 
former leads to the work jaws. 

ELECTRIC ARC WELDING 

This method bears no relation to the one just con- 
sidered, except that the source of heat is the same in 
both cases. Arc welding makes use of the flame 
produced by the voltaic arc in practically the same 
way that oxy-acetylene welding uses the flame from 
the gases. 

If the ends of two pieces of carbon through which a 
current of electricity is flowing while they are in con- 
tact are separated from each other quite slowly, a 
brilliant arc of flame is formed between them which 
consists mainly of carbon vapor. The carbons are 
consumed by combination with the oxygen in the air 
and through being turned to a gas under the intense 
heat. 

The most intense action takes place at the center of 
the carbon which carries the positive current and this 
is the point of greatest heat. The temperature at this 
point in the arc is greater than can be produced by 
any other means under human control. 

An arc may be formed between pieces of metal, 
called electrodes, in the same way as between carbon. 



ELECTRIC WELDING 161 

The metallic arc is called a flaming arc and as the 
metal of the electrode burns with the heat, it gives the 
flame a color characteristic of the material being used. 
The metallic arc may be drawn out to a much greater 
length than one formed between carbon electrodes. 

Arc welding is carried out by drawing a piece of 
carbon which is of negative polarity away from the 
pieces of metal to be welded while the metal is made 
positive in polarity. The negative wire is fastened 
to the carbon electrode and the work is laid on a 
table made of cast or wrought iron to which the posi- 
tive wire is made fast. The direction of the flame is 
then from the metal being welded to the carbon and 
the work is thus prevented from being saturated 
with carbon, which would prove very detrimental to 
its strength. A secondary advantage is found in the 
fact that the greatest heat is at the metal being welded 
because of its being the positive electrode. 

The carbon electrode is usually made from one 
quarter to one and a half inches in diameter and from 
six to twelve inches in length. The length of the arc 
may be anywhere from one inch to four inches, de- 
pending on the size of the work being handled. 

While the parts are carefully insulated to avoid 
danger of shock, it is necessary for the operator to 
wear rubber gloves as a further protection, and to 
wear some form of hood over the head to shield him 
against the extreme heat liberated. This hood may 
be made from metal, although some material that does 
not conduct electricity is to be preferred. The work 
is watched through pieces of glass formed with one 
sheet, which is either blue or green, placed over an- 
other which is red. Screens of glass are sometimes 
used without the head protector. Some protection 



162 WELDING 

for the eyes is absolutely necessary because of the 
intense white light. 

It is seldom necessary to preheat the work as with 
the gas processes, because the heat is localized at the 
point of welding and the action is so rapid that the 
expansion is not so great. The necessity of pre- 
heating, however, depends entirely on the material, 
form and size of the work being handled. The same 
advice applies to arc welding as to the gas flame 
method but in a lesser degree. Filling rods are used 
in the same way as with any other flame process. 

It is the purpose of this explanation to state the 
fundamental principles of the application of the elec- 
tric arc to welding metals, and by applying the prin- 
ciples the following questions will be answered : 

What metals can be welded by the electric arc? 

What difficulties are to be encountered in applying 
the electric arc to welding? 

What is the strength of the weld in comparison with 
the original piece? 

What is the function of the arc welding machine 
itself? 

What is the comparative application of the electric 
arc and the oxy-acetylene method and others of a 
similar nature ? 

The answers to these questions will make it possi- 
ble to understand the application of this process to 
any work. In a great many places the use of the arc 
is cutting the cost of welding to a very small frac- 
tion of what it would be by any other method, so 
that- the importance of this method may be well un- 
derstood. 

Any two metals which are brought to the melting 
temperature and applied to each other will adhere so 



ELECTRIC WELDING 163 

that they are no more apt to break at the weld than 
at any other point outside of the weld. It is the 
property of all metals to stick together under these 
conditions. The electric arc is used in this connec- 
tion merely as a heating agent. This is its only func- 
tion in the process. 

It has advantages in its ease of application and the 
cheapness with which heat can be liberated at any 
given point by its use. There is nothing in connec- 
tion with arc welding that the above principles will 
not answer; that is, that metals at the melting point 
will weld and that the electric arc will furnish the 
heat to bring them to this point. As to the first ques- 
tion, what metals can be welded, all metals can be 
welded. 

The difficulties which are encountered are as fol- 
lows: 

In the case of brass or zinc, the metals will be cov- 
ered with a coat of zinc oxide before they reach a 
welding heat. This Zinc oxide makes it impossible for 
two clean surfaces to come together and some method 
has to be used for eliminating this possibility and 
allowing the two surfaces to join without the possi- 
bility of the oxide intervening. The same is true of 
aluminum, in which the oxide, alumina, will be 
formed, and with several other alloys comprising ele- 
ments of different melting points. 

In order to eliminate these oxides, it is necessary 
in practical work, to puddle the weld ; this is, to have 
a sufficient quantity of molten metal at the weld so 
that the oxide is floated away. "When this is done, 
the two surfaces which are to be joined are covered 
with a coat of melted metal on which floats the oxide 
and other impurities. The two pieces are thus allowed 



164 WELDING 

to join while their surfaces are protected. This pre- 
caution is not necessary in working with steel except 
in extreme cases. 

Another difficulty which is met with in the welding 
of a great many metals is their expansion under heat, 
which results in so great a contraction when the weld 
cools that the metal is left with a considerable strain 
on it. In extreme cases this will result in cracking 
at the weld or near it. To eliminate this danger it 
is necessary to apply heat either all over the piece to 
be welded or at certain points. In the case of cast 
iron and sometimes with copper it is necessary to 
anneal after welding, since otherwise the welded 
pieces will be very brittle on account of the chilling. 
This is also true of malleable iron. 

Very thin metals which are welded together and 
are not backed up by something to carry away the 
excess heat, are very apt to burn through, leaving a 
hole where the weld should be. This difficulty can 
be eliminated by backing up the weld with a metal 
face or by decreasing the intensity of the arc so that 
this melting through will not occur. However, the 
practical limit for arc welding without backing up 
the work with a metal face or decreasing the intensity 
of the arc is approximately 22 gauge, although thin-k 
ner metal can be welded by a very skillful and care- 
ful operator. 

One difficulty with arc welding is the lack of skill- 
ful operators. This method is often looked upon as 
being something" out of the ordinary and governed by 
laws entirely different from other welding. As a 
matter of fact, it does not take as much skill to make 
a good arc weld as it does to make a good weld in a 
forge fire as the blacksmith does it. There are few 



ELECTRIC WELDING 165 

jobs which cannot be handled successfully by an oper- 
ator of average intelligence with one week's instruc- 
tions, although his work will become better and better 
in quality as he continues to use the arc. 

Now comes the question of the strength of the weld 
after it has been made. This strength is equally as 
great as that of the metal that is used to make the 
weld. It should be remembered, however, that the 
metal which goes into the weld is put in there as a 
casting and has not been rolled. This would make 
the strength of the weld as great as the same metal 
that is used for filling if in the cast form. 

Two pieces of steel could be welded together hav- 
ing a tensile strength at the weld of 50,000 pounds. 
Higher strengths than this can be obtained by the 
use of special alloys for the filling material or by 
rolling. Welds with a tensile strength as great as 
mentioned will give a result which is perfectly satis- 
factory in almost all cases. 

There are a great many jobs where it is possible to 
fill up the weld, that is, make the section at the point 
of the weld a little larger than the section through the 
the rest of the piece. By doing this, the disadvantages 
of the weld being in the form of a casting in compari- 
son with the rest of the piece being in the form of 
rolled steel can be overcome, and make the weld itself 
even stronger than the original piece. 

The next question is the adaptability of the electric 
arc in comparison with forge fire, oxy-acetylene or 
other method. The answer is somewhat difficult if 
made general. There are no doubt some cases where 
the use of a drop hammer and forge fire or the use of 
the oxy-acetylene torch will make, all things being 
considered, a better job than the use of the electric 



166 WELDING 

arc, although a case where this is absolutely proved is 
rare. 

The electric arc will melt metal in a weld for less 
than the same metal can be melted by the use of the 
oxy-acetylene torch, and, on account of the fact that 
the heat can be applied exactly where it is required 
and in the amount required, the arc can in almost all 
cases supply welding heat for less cost than a forge 
fire or heating furnace. 

The one great advantage of the oxy-acetylene 
method in comparison with other methods of welding 
is the fact that in some cases of very thin sheet, the 
weld can be made somewhat sooner than is possible 
otherwise. "With metal of 18 gauge or thicker, this 
advantage is eliminated. In cutting steel, the oxy- 
acetylene torch is superior to almost any other pos- 
sible method. 

Arc Welding Machines. — A consideration of the 
function and purpose of the various types of arc weld- 
ing machines shows that the only reason for the use 
of any machine is either for conversion of the cur- 
rent from alternating to direct, or, if the current is 
already direct, then the saving in the application of 
this current in the arc. 

It is practically out of the question to apply an 
alternating current arc to welding for the reason that 
in any arc practically all the heat is liberated at the 
positive electrode, which means that, in alternating 
current, half the heat is liberated at each electrode 
as the current changes its direction of flow or alter- 
nates. Another disadvantage of the alternating arc is 
that it is difficult of control and application. 

In all arc welding by the use of the carbon arc, 
the positive electrode is made the piece to be welded, 



ELECTRIC WELDING 167 

while in welding with metallic electrodes this may 
be either the piece to be welded of the rod that is 
used as a filler. The voltage across the arc is a vari- 
able quantity, depending on the length of the flame, 
its temperature and the gases liberated in the arc. 
"With a carbon electrode the voltage will vary from 
zero to forty-five volts. "With the metallic electrode 
the voltage will vary from zero to thirty volts. It is, 
therefore, necessary for the welding machine to be 
able to furnish to the arc the requisite amount of cur- 
rent, this amount being varied, and furnish it at all 
times at the voltage required. 

The simplest welding apparatus is a resistance in 
series with the arc. This is entirely satisfactory in 
every way except in cost of current. By the use of 
resistance in series with the arc and using 220 volts 
as the supply, from eighty to ninety per cent of the 
current is lost in heat at the resistance. Another 
disadvantage is the fact that most materials change 
their resistance as their temperature changes, thus 
making the amount of current for the arc a variable 
quantity, depending on the temperature of the resist- 
ance. 

There have been various methods originated for 
saving the power mentioned and a good many ma- 
chines have been put on the market for this pur- 
pose. All of them save some power over what a plain 
resistance would use. Practically all arc welding ma- 
chines at the present time are motor generator sets, 
the motor of which is arranged for the supply volt- 
age and current, this motor being direct connected to 
a compound wound generator delivering approxi- 
mately seventy-five volts direct current. Then by the 
use of a resistance, this seventy-five volt supply is 



168 WELDING 

applied to the arc. Since the voltage across the arc 
will vary from zero to fifty volts, this machine will 
save from zero up to seventy per cent of the power 
that the machine delivers. The rest of the power, of 
course, has to be dissipated in the resistance used in 
series with the arc. 

A motor generator set which can be purchased from 
any electrical company, with a long piece of fence wire 
wound around a piece of asbestos, gives results equally 
as good and at a very small part of the first cost. 

It is possible to construct a machine which will 
eliminate all losses in the resistance ; in other words, 
eliminate all resistance in series with the arc. A 
machine of this kind will save its cost within a very 
short time, providing the welder is used to any extent. 

Putting it in figures, the results are as follows for 
average conditions. Current at 2c per kilow r att hour, 
metallic electrode arc of 150 amperes, carbon arc 500 
amperes; voltage across the metallic electrode arc 20, 
voltage across the carbon arc 35. Supply current 220 
volts, direct. In the case of the metallic electrode, if 
resistance is used, the cost of running this arc is sixty- 
six cents per hour. With the carbon electrode, $2.20 
per hour. If a motor generator set with a seventy 
volt constant potential machine is used for a welder, 
the cost will be as follows : 

Metallic electrode 25.2c. Carbon electrode 84c per 
hour. With a machine which will deliver the required 
voltage at the arc and eliminate all the resistance in 
series with the arc, the cost will be as follows: Me- 
tallic electrode 7.2c per hour; carbon electrode 42c 
per hour. This is with the understanding that the 
arc is held constant and continuously at its full value. 
This, however, is practically impossible and the actual 



ELECTRIC WELDING -.69 

load factor is approximately fifty per cent, wiiich 
would mean that operating a welder as it is usually 
operated, this result will be reduced to one-half of 
that stated in all cases. 



CHAPTER VII 
HAND FOKGING AND WELDING 

Smithing, or blacksmithing, is the process of work- 
ing heated iron, steel or other metals by forging, bend- 
ing or welding them. 

The Forge. — The metal is heated in a forge con- 
sisting of a shallow pan for holding the fire, in the 
center of which is an opening from below through 
which air is forced to make a hot fire. 




Figure 48. — Tuyere Construction on a Forge 

Air is forced through this hole, called a " tuyere " 
(Figure 48) by means of a hand bellows, a rotary 
fan operated with crank or lever, or with a fan driven 
from an electric motor. The harder the air is driven 
into the fire above the tuyere the more oxygen is fur- 
nished and the hotter the fire becomes. 

Directly below the tuyere is an opening through 
which the ashes that drop from the fire may be cleaned 
out. 

170 



HAND FORGING AND WELDING 171 

The Fire. — The fire is made by placing a small 
piece of waste soaked in oil, kerosene or gasoline, over 
the tuyere, lighting the waste, then starting the fan 
or blower slowly. Gradually cover the waste, while 
it is burning brightly, with a layer of soft coal. The 
coal will catch fire and burn after the waste has been 
consumed. A piece of waste half the size of a per- 
son's hand is ample for this purpose. 

The fuel should be "smithing coal." A lump of 
smithing coal breaks easily, shows clean and even on 
all sides and should not break into layers. The coal 
is broken into fine pieces and wet before being used 
on the fire. 

The fire should be kept deep enough so that there is 
always three or four inches of fire below the piece of 
metal to be heated and there should be enough fire 
above the work so that no part of the metal being 
heated comes in contact with the air. The fire should 
be kept as small as possible while following these rules 
as to depth. 

To make the fire larger, loosen the coal around the 
edges. To make the fire smaller, pack wet coal around 
the edges in a compact mass and loosen the fire in 
the center. Add fresh coal only around the edges of 
the fire. It will turn to coke and can then be raked 
onto the fire. Blow only enough air into the fire to 
keep it burning brightly, not so much that the fire is 
blown up through the top of the coal pack. To pre- 
vent the fire from going out between jobs, stick a piece 
of soft wood into it and cover with fresh wet coal. 

Tools. — The hammer is a ball pene, or blacksmith's 
hammer, weighing about a pound and a half. 

The sledge is a heavy hammer, weighing from 5 to 
20 pounds and having a handle 30 to 36 inches long. 



172 



WELDING 



The anvil is a heavy piece of wrought iron (Figure 
49 ) , faced with steel and having four legs. It has a 
pointed horn on one end, an overhanging tail on the 
other end and a flat top. In the tail there is a square 
hole called the "hardie" hole and a round one called 
the "spud" hole. 

Tongs, with handles about one foot long and jaws 
suitable for holding the work, are used. To secure a 
firm grip on the work, the jaws may be heated red 




Figure 49. — Anvil, Showing Horn, Tail, Hardie Hole and Spud Hole 



hot and hammered into shape over the piece to be 
held, thus giving a properly formed jaw. Jaws should 
touch the work along their entire length. 

The set hammer is a hammer, one end of whose head 
is square and flat, and from this face the head tapers 
evenly to the other face. The large face is about l 1 /^ 
inches square. 

The flatter is a hammer having one face of its head 
flat and about 2y 2 inches square. 

Swages are hammers having specially formed faces 
for finishing rounds, squares, hexagons, ovals, tapers, 
etc. 



HAND FORGING AND WELDING 173 

Fullers are hammers having a rounded face, long 
in one direction. They are used for spreading metal 
in one direction only. 

The hardy is a form of chisel with a short, square 
shank which may be set into the hardie hole for cut- 
ting off hot bars. 

Operations. — Blacksmithing consists of bending, 
drawing or upsetting with the various hammers, or 
in punching holes. 

Bending is done over the square corners of the 
anvil if square cornered bends are desired, or over the 
horn of the anvil if rounding bends, eyes, hooks, etc., 
are wanted. 

To bend a ring or eye in the end of a bar, first figure 
the length of stock needed by multiplying the diam- 
eter of the hole by 31/7, then heat the piece to a 
good full red at a point this distance back from the 
end. Next bend the iron over at a 90 degree angle 
(square) at this point. Next, heat the iron from 
the. bend just made clear to the point and make the 
eye by laying the part that was bent square over the 
horn of the anvil and bending the extreme tip into 
part of a circle. Keep pushing the piece farther and 
farther over the horn of the anvil, bending it as you 
go. Do not hammer directly over the horn of the 
anvil, but on the side where you are doing the 
bending. 

To make the outside of a bend square, sharp and 
full, rather than slightly rounding, the bent piece 
must be laid edgewise on the face of the anvil. That 
is, after making the bend over the corner of the anvil, 
lay the piece on top of the anvil so that its edge and 
not the flat side rests on the anvil top. With the work 
in this position, strike directly against the corner 



174 WELDING 

with the hammer so that the blows come in line, first 
with one leg of the work, then the other, and always 
directly on the corner of the piece. This operation 
cannot be performed by laying the wwk so that one 
leg hangs over the anvil's corner. 

To make a shoulder on a rod or bar, heat the work 
and lay flat across the top of the anvil with the point 
at which the shoulder is desired at the edge of the 
anvil. Then place the set hammer on top of the piece, 
with the outside edge of the set hammer directly over 
the edge of the anvil. While hammering in this posi- 
tion keep the work turning continually. 

To draw stock means to make it longer and thinner 
by hammering. A piece to be drawn out is usually 
laid across the horn of the anvil while being struck 
with the hammer. The metal is then spread in only 
one direction in place of being spread in every direc- 
tion, as it would be if laid on the anvil face. To 
draw the work, heat it to as high a temperature as it 
will stand without throwing sparks and burning. The 
fuller may be used for drawing metal in place of lay- 
ing the work over the horn of the anvil. 

When drawing round stock, it should be first drawn 
out square, and when almost down to size it may be 
rounded. When pointing stock, the same rule of first 
drawing out square applies. 

Upsetting means to make a piece shorter in length 
and greater in thickness or width, or both shorter and 
thicker. To upset short pieces, heat to a bright red at 
the place to be upset, then stand on end on the ahvil 
face and hammer directly down on top until of the 
right form. Longer pieces may be swung against the 
anvil or placed upright on a heavy piece of metal 
lying on the floor or that is sunk into the floor. While 



HAND FORGING AND WELDING 175 

standing on this heavy piece the metal may be upset 
by striking down on the end with a heavy hammer or 
the sledge. If a bend appears while upsetting, it 
should be straightened by hammering back into shape 
on the anvil face. 

Light blows affect the metal for only a short dis- 
tance from the point of striking, bnt heavy blows tend 
to swell the metal more equally through its entire 
length. In driving rivets that should fill the holes, 
heavy blows should be struck, but to shape the end of 
a rivet or to make a head on a rod, light blows should 
be used. 

The part of the piece that is heated most will upset 
the most. 

To punch a hole through metal, use a tool steel 
punch with its end slightly tapering to a size a little 
smaller than the hole to be punched. The end of 
the punch must be square across and never pointed or 
rounded. 

First drive the punch part way through from one 
side and then turn the work over. When you turn 
it over, notice where the bulge appears and in that 
way locate the hole and drive the punch through from 
the second side. This makes a cleaner and more even 
hole than to drive completely through from one side. 
"When the punch is driven in from the second side, 
the place to be punched through should be laid over 
the spud hole in the tail of the anvil and the piece 
driven out of the work. 

Work when hot is larger than it will be after cool- 
ing. This must be remembered when fitting parts or 
trouble will result. A two-foot bar of steel will be 
y± inch longer when red hot than when cold. 



176 WELDING 

The temperatures of iron correspond to the fol- 
lowing colors : 

Dullest red seen in the dark 878° 

Dullest red seen in daylight 887° . 

Dull red 1100° 

Full red . 1370° 

Light red 1550° 

Orange 1650° 

Light orange 1725° 

Yellow 1825° 

Light yellow 1950° 

Bending Pipes and Tubes. — It is difficult to make 
bends or curves in pipes and tubing without leaving 
a noticeable bulge at some point of the work. Seam- 
less steel tubing may be handled without very great 
danger of this trouble if care is used, but iron pipe, 
having a seam running lengthwise, must be given 
special attention to avoid opening the seam. 

Bends may be made without kinking if the tube or 
pipe is brought to a full red heat all the way around 
its circumference and at the place where the bend 
is desired. Hold the cool portion solidly in a vise 
and, by taking hold of the free end, bend very slowly 
and with a steady pull. The pipe must be kept at 
full red heat with the flames from one or more torches 
and must not be hammered to produce the bend. 
If a sufficient purchase cannot be secured on the free 
end by the hand, insert a piece of rod or a smaller 
pipe into the opening. 

While making the bend, should small bulges appear, 
they may be hammered back into shape before pro- 
ceeding with the work. 



HAND FORGING AND WELDING 177 

Tubing or pipes may be bent while being held 
between two flat metal surfaces while at a bright 
red heat. The metal plates at each side of the work 
prevent bulging. 

Another method by which tubing may be bent 
consists of filling completely with tightly packed sand 
and fitting a solid cap or plug at each end. 

Thin brass tubing may be filled with melted resin 
and may be bent after the resin cools. To remove 
the resin it is necessary to heat the tube, allowing 
it to run out. 

Large jobs of bending should be handled in special 
pipe bending machines in which the work is forced 
through formed rolls which prevent its bulging. 

WELDING 

Welding with the heat of a blacksmith forge fire, 
or a coal or illuminating gas fire, can only be per- 
formed with iron and steel because of the low heat 
which is not localized as with the oxy-acetylene and 
electric processes. Iron to be welded in this manner 
is heated until it reaches the temperature indicated 
by an orange color, not white, as is often stated, this 
orange color being slightly above 1600 degrees Fah- 
renheit. Steel is usually welded at a bright red heat 
because of the danger of oxidizing or burning the 
metal if the temperature is carried above this point. 

The Fire. — If made in a forge, the fire should be 
built from good smithing coal or, better still, from 
coke. Gas fires are, of course, produced by suitable 
burners and require no special preparation except 
adjustment of the heat to the proper degree for the 
size and thickness of the metal being welded so that 
it will not be burned. 



178 WELDING 

A coal fire used for ordinary forging operations 
should not be used for welding because of the im- 
purities it contains. A fresh fire should be built 
with a rather deep bed of coal, four to eight inches 
being about right for work ordinarily met with. The 
fire should be kept burning until the coal around the 
edges has been thoroughly coked and a sufficient 
quantity of fuel should be on and around the fire 
so that no fresh coal will have to be added while 
working. 

After the coking process has progressed sufficiently, 
the edges should be packed down and the fire made 
as small as possible while still surrounding the ends 
to be joined. The fire should not be altered by poking 
it while the metal is being heated. The best form 
of fire to use is one having rather high banks of 
coked coal on each side of the mass, leaving an open- 
ing or channel from end to end. This will allow the 
added fuel to be brought down on top of the fire 
with a small amount of disturbance. 

Preparing to Weld.—li the operator is not familiar 
with the metal to be handled, it is best to secure a 
test piece if at all possible and try heating it and 
joining the ends. Various grades of iron and steel 
call for different methods of handling and for dif- 
ferent degrees of heat, the proper method and tem- 
perature being determined best by actual test under 
the hammer. 

The form of the pieces also has a great deal to do 
with their handling, especially in the case of a more 
or less inexperienced workman. If the pieces are 
at all irregular in shape, the motions should be gone 
through with before the metal is heated and the best 
positions on the anvil as well as in the fire deter- 



HAND FORGING AND WELDING 179 

mined with regard to the convenience of the workman 
and speed of handling the work after being brought 
to a welding temperature. Unnatural positions at 
the anvil should be avoided as good work is most 
difficult of performance under these conditions. 

Scarfing, — While there are many forms of welds, 
depending on the relative shape of the pieces to be 
joined, the portions that are to meet and form one 
piece are always shaped in the same general way, 
this shape being called a "scarf." The end of a 
piece of work, when scarfed, is tapered off on one 
side so that the extremity comes to a rather sharp 
edge. The other side of the piece is left flat and a 



Figure 50. — Scarfing Ends of Work Ready for Welding 

continuation in the same straight plane with its side 
of the whole piece of work. The end is then in the 
form of a bevel or mitre joint (Figure 50). 

Scarfing may be produced in any one of several 
ways. The usual method is to bring the ends to a 
forging heat, at which time they are upset to give 
a larger body of metal at the ends to be joined. This 
body of metal is then hammered down to the taper 
on one side, the length of the tapered portion being 
about one and a half times the thickness of the whole 
piece being handled. Each piece should be given 
this shape before proceeding farther. 

The scarf may be produced by filing, sawing or 
chiseling the ends, although this is not good practice 
because it is then impossible to give the desired upset 
and additional metal for the weld. This added thick- 



180 WELDING 

ness is called for by the fact that the metal burns 
away to a certain extent or turns to scale, which is 
removed before welding. 

When the two ends have been given this shape 
they should not fit as closely together as might be 
expected, but should touch only at the center of the 
area to be joined (Figure 51). That is to say, the 
surface of the beveled portion should bulge in the 
middle or should be convex in shape so that the edges 
are separated by a little distance when the pieces are 
laid together with the bevels toward each other. 
This is done so that the scale which is formed on the 




Figure 51. — Proper Shape of Scarfed Ends 

metal by the heat of the fire can have a chance to 
escape from the interior of the weld as the two parts 
are forced together. 

If the scarf were to be formed with one or more 
of the edges touching each other at the same time 
or before the centers did so, the scale would be im- 
prisoned w T ithin the body of the weld and would cause 
the finished work to be weak, while possibly giving 
a satisfactory appearance from the outside. 

Fluxes. — In order to assist in removing the scale 
and other impurities and to make the welding sur- 
faces as clean as possible while being joined, various 
fluxing materials are used as in other methods of 
welding. 

For welding iron, a flux of white sand is usually 
used, this material being placed on the metal after 
it has been brought to a red heat in the fire. Steel 



HAND FORGING AND WELDING 181 

is welded with dry borax powder, this flux being 
applied at the same time as the iron flux just men- 
tioned. Borax may also be used for iron welding 
and a mixture of borax with steel borings may also 
be used for either class of work. Mixtures of sal 
ammoniac with borax have been successfully used, 
the proportions being about four parts of borax to 
one of sal ammoniac. Various prepared fluxing 
powders are on the market for this work, practically 
all of them producing satisfactory results. 

After the metal has been in the fire long enough 
to reach a red heat, it is removed temporarily and, 
if small enough in size, the ends are dipped into a 
box of flux. If the pieces are large, they may simply 
be pulled to the edge of the fire and the flux then 
sprinkled on tlie portions to be joined. A greater 
quantity of flux is required in forge welding than 
in electric or oxy-acetylene processes because of the 
losses in the fire. After the powder has been applied 
to the surfaces, the work is returned to the fire and 
heated to the welding temperature. 

Heating the Work. — After being scarfed, the two 
pieces to be welded are placed in the fire and brought 
to the correct temperature. This temperature can 
only be recognized by experiment and experience. 
The metal must be just below that point at which 
small sparks begin to be thrown out of the fire and 
naturally this is a hard point to distinguish. At the 
welding heat the metal is almost ready to flow and is 
about the consistency of putty. Against the back- 
ground of the fire and coal the color appears to be 
a cream or very light yellow and the work feels soft 
as it is handled. 

It is absolutely necessary that both parts be heated 



182 WELDING 

uniformly and so that they reach the welding tern-* 
perature at the same time. For this reason they 
should be as close together in the fire as possible and 
side by side. When removed to be hammered to- 
gether, time is saved if they are picked up in such 
a way that when laid together naturally the beveled 
surfaces come together. This makes it necessary that 
the workman remember whether the scarfed side is 
up or down, and to assist in this it is a good thing 
to mark the scarfed side with chalk or in some other 
noticeable manner, so that no mistake will be made 
in the hurry of placing the work on the anvil. 

The common practice in heating allows the tem- 
perature to rise until the small white sparks are seen 
to come from the fire. Any heating above this point 
will surely result in burning that will ruin the iron 
or steel being handled. The best welding heat can 
be discerned by the appearance of the metal and 
its color after experience has been gained with this 
particular material. Test welds can be made and 
then broken, if possible, so that the strength gained 
through different degrees of heat can be known 
before attempting more important work. 

Welding. — When the work has reached the welding 
temperature after having been replaced in the fire 
with the flux applied, the two parts are quickly 
tapped to remove the loose scale from their surfaces. 
They are then immediately laid across the top of the 
anvil, being placed in a diagonal position if both 
pieces are straight. The lower piece is rested on the 
anvil first with the scarf turned up and ready to 
receive the top piece in the position desired. The 
second piece must be laid in exactly the position it 
is to finally occupy because the two parts will stick 



HAND FORGING AND WELDING 183 

together as soon as they touch and they cannot well 
be moved after having once been allowed to come in 
contact with each other. This part of the work must 
be done without any unnecessary loss of time because 
the comparatively low heat at which the parts weld 
allows them to cool below the working temperature 
in a few seconds. 

The greatest difficulty will be experienced in with- 
drawing the metal from the fire before it becomes 
burned and in getting it joined before it cools below 
this critical point. The beveled edges of the scarf 
are, of course, the first parts to cool and the weld 
must be made before they reach a point at which they 
will not join, or else the work will be defective in 
appearance and in fact. 

If the parts being handled are of such a shape that 
there is danger of bending a portion back of the 
weld, this part may be cooled by quickly dipping it 
into water before laying the work on the anvil to 
be joined. 

The workman uses a heavy hand hammer in making 
the joint, and his helper, if one is employed, uses a 
sledge. "With the two parts of the work in place 
on the anvil, the workman strikes several light blows, 
the first ones being at a point directly over the center 
of the weld, so that the joint will start from this 
point and be worked toward the edges. After the 
pieces have united the helper strikes alternate blows 
with his sledge, always striking in exactly the same 
place as the last stroke of the workman. The hammer 
blows are carried nearer and nearer to the edges of 
the weld and are made steadily heavier as the work 
progresses. 

The aim during the first part of the operation 



184 WELDING 

should be to make a perfect joint, with every part 
of the surfaces united, and too much attention should 
not be paid to appearance, at least not enough to 
take any chance with the strength of the work, 

It will be found, after completion of the weld, that 
there has been a loss in length equal to one-half the 
thickness of the metal being welded. This loss is 
occasioned by the burned metal and the scale which 
has been formed. 

Finishing the Weld. — If it is possible to do so, the 
material should be hammered into the shape that it 
should remain with the same heat that was used for 




Figure 52. — Upsetting and Scarfing the End of a Rod 

welding. It will usually be found, however, that the 
metal has cooled below the point at which it can be 
worked to advantage. It should then be replaced in 
the fire and brought back to a forging heat. 

While shaping the work at this forging heat every 
part that has been at a red heat should be ham- 
mered with uniformly light and even blows as it cools. 
This restores the grain and strength of the iron or 
steel to a great extent and makes the unavoidable 
weakness as small as possible. 

Forms of Welds. — The simplest of all welds is that 
called a "lap weld." This is made between the ends 
of two pieces of equal size and similar form by 
scarfing them as described and then laying one on 
top of the other while they are hammered together. 

A butt weld (Figure 52) is made between the ends 



HAND FORGING AND WELDING 185 

of two pieces of shaft or other bar shapes by upsetting 
the ends so that they have a considerable flare and 
shaping the face of the end so that it is slightly 
higher in the center than around the edges, this being 
done to make the centers come together first. The 
pieces are heated and pushed into contact, after which 
the hammering is done as with any other weld. 

A form similar to the butt weld in some ways is 
used for joining the end of a bar to a flat surface 
and is called a jump weld. The bar is shaped in 
the same way as for a butt weld. The flat plate 




Figure 53. — Scarfing for a T Weld 

may be left as it is, but if possible a depression 
should be made at the point where the shaft is to 
be placed. With the two parts heated as usual, the 
bar is dropped into position and hammered from 
above. As soon as the center of the weld has been 
made perfect, the joint may be finished with a fuller 
driven all the way around the edge of the joint. 

When it is required to join a bar to another bar 
or to the edge of any piece at right angles the work 
is called a "T" weld from its shape when complete 
(Figure 53). The end of the bar is scarfed as 
described and the point of the other bar or piece 
where the weld is to be made is hammered so that it 
tapers to a thin edge like one-half of a circular 



186 WELDING 

depression. The pieces are then laid together and 
hammered as for a lap weld. 

The ends of heavy bar shapes are often joined 
with a "V," or cleft, weld. One bar end is shaped 
so that it is tapering on both sides and comes to a 
broad edge like the end of a chisel. The other bar 
is heated to a forging temperature and then slit open 
in a lengthwise direction so that the V-shaped open- 
ing which is formed will just receive the pointed edge 
of the first piece. With the work at welding heat, 
the two parts are driven together by hammering on 
the rear ends and the hammering then continues as 




Figure 54.— Splitting Ends to Be Welded in Thin Work 

with a lap weld, except that the work is turned over 
to complete both sides of the joint. 

The forms so far described all require that the 
pieces be laid together in the proper position after 
removal from the fire, and this always causes a slight 
loss of time and a consequent lowering of the tem- 
perature. "With very light stock, this fall of tem- 
perature would be so rapid that the weld would be 
unsuccessful, and in this case the "lock" weld is 
resorted to. The ends of the two pieces to be joined 
are split for some distance back, and one-half of each 
end is bent up and the other half down (Figure 54). 
The two are then pushed together and placed in the 
fire in this position. When the welding heat is 
reached, it is only necessary to take the work out of 
the fire and hammer the parts together, inasmuch as 
they are already in the correct position. 



HAND FORGING AND WELDING 187 

Other forms of welds in which the rjarts are too 
small to retain their heat, can be made by first 
riveting them together or cutting them so that they 
can be temporarily fastened in any convenient way 
when first placed in the fire. 



CHAPTER VIII 
SOLDERING, BRAZING AND THERMIT WELDING 

SOLDERING 

Common solder is an alloy of one-half lead with 
one-half tin, and is called "half and half." Hard 
solder is made with two-thirds tin and one-third lead. 
These alloys, when heated, are used to join surfaces 
of the same or dissimilar metals such as copper, brass, 
lead, galvanized iron, zinc, tinned plate, etc. These 
metals are easily joined, but the action of solder with 
iron, steel and aluminum is not so satisfactory and 
requires greater care and skill. 

The solder is caused to make a perfect union with 
the surfaces treated with the help of heat from a 
soldering iron. The soldering iron is made from a 
piece of copper, pointed at one end and with the 
other end attached to an iron rod and wooden handle. 
A flux is used to remove impurities from the joint 
and allow the solder to secure a firm union with the 
metal surface. The iron, and in many cases the work, 
is heated with a gasoline blow torch, a small gas 
furnace, an electric heater or an acetylene and air 
torch. 

The gasoline torch which is most commonly used 
should be filled two-thirds full of gasoline through 
the hole in the bottom, which is closed by a screw 
plug. After working the small hand pump for 10 
to 20 strokes, hold the palm of your hand over the 
end of the large iron tube on top of the torch and 
open the gasoline needle valve about a half turn. 
Hold the torch so that the liquid runs down into 

188 



SOLDERING, BRAZING AND THERMIT WELDING 189 

the cup below the tube and fills it. Shut the gasoline 
needle valve, wipe the hands dry, and set fire to 
the fuel in the cup. Just as the gasoline fire goes 
out, open the gasoline needle valve about a half turn 
and hold a lighted match at the end of the iron tube 
to ignite the mixture of vaporized gasoline and air. 
Open or close the needle valve to secure a flame about 
4 inches long. 

On top of the iron tube from which the flame issues 
there is a rest for supporting the soldering iron with 
the copper part in the flame. Place the iron in the 
flame and allow it to remain until the copper becomes 
very hot, not quite red, but almost so. 

A new soldering iron or one that has been misused 
will have to be "tinned" before using. To do this, 
take the iron from the fire while very hot and rub 
the tip on some flux or dip it into soldering acid. 
Then rub the tip of the iron on a stick of solder or 
rub the solder on the iron. If the solder melts off the 
stick without coating the end of the iron, allow a 
few drops to fall on a piece of tin plate, then rub 
the end of the iron on the tin plate with considerable 
force. Alternately rub the iron on the solder and 
dip into flux until the tip has a coating of bright 
solder for about half an inch from the end. If the 
iron is in very bad shape, it may be necessary to 
scrape or file the end before dipping in the flux for 
the first time. After the end of the iron is tinned 
in this way, replace it on the rest of the torch so that 
the tinned point is not directly in the flame, turning 
the flame down to accomplish this. 

Flux. — The commonest flux, which is called "sol- 
dering acid," is made by placing pieces of zinc in 
muriatic (hydrochloric) acid contained in a heavy 



190 WELDING 

glass or porcelain dish. There will be bubbles and 
considerable heat evolved and zinc should be added 
until this action ceases and the zinc remains in the 
liquid, which is now chloride of zinc. 

This soldering acid may be used on any metal to 
be soldered by applying with a brush or swab. For 
electrical work, this acid should be made neutral by 
the addition of one part ammonia and one part water 
to each three parts of the acid. This neutralized flux 
will not corrode metal as will the ordinary acid. 

Powdered resin makes a good flux for lead, tin 
plate, galvanized iron and aluminum. Tallow, olive 
oil, beeswax and vaseline are also used for this pur- 
pose. Muriatic acid may be used for zinc or gal- 
vanized iron without the addition of the zinc, as de- 
scribed in making zinc- chloride. The addition of 
two heaping teaspoonfuls of sal ammoniac to each 
pint of the chloride of zinc is sometimes found to 
improve its action. 

Soldering Metal Parts. — All surfaces to be joined 
should be fitted to each other as accurately as pos- 
sible and then thoroughly cleaned with a file, emery 
cloth, scratch bush or by dipping in lye. "Work may 
be cleaned by dipping it into nitric acid which has 
been diluted with an equal volume of water. The 
work should be heated as hot as possible without 
danger of melting, as this causes the solder to flow 
better and secure a much better hold on the surfaces. 
Hard solder gives better results than half and half, 
but is more difficult to work. It is very important 
that the soldering iron be kept at a high heat during 
all work, otherwise the solder will only stick to the 
surfaces and will not join with them. 

Sweating is a form of soldering in which the sur- 



SOLDERING, BRAZING AND THERMIT WELDING 191 

faces of the work are first covered with a thin layer 
of solder by rubbing them with the hot iron after 
it has been dipped in or touched to the soldering 
stick. These surfaces are then placed in contact 
and heated to a point at which the solder melts and 
unites. Sweating is much to be preferred to ordinary 
soldering where the form of the work permits it. 
This is the only method which should ever be used 
when a fitting is to be placed over the end of a length 
of tube. 

Soldering Holes. — Clean the surfaces for some dis- 
tance around the hole until they are bright, and apply 
flux while holding the hot iron near the hole. Touch 
the tip of the iron to some solder until the solder is 
picked up on the iron, and then place this solder, 
which was just picked up, around the edge of the 
hole. It will leave the soldering iron and stick to 
the metal. Keep adding solder in this way until the 
hole has been closed up by working from the edges 
and building toward the center. After the hole is 
closed, apply more flux to the job and smooth over 
with the hot iron until there are no rough spots. 
Should the solder refuse to flow smoothly, the iron 
is not hot enough. 

Soldering Seams. — Clean back from the seam or 
split for at least half an inch all around and then 
build up the solder in the same way as was done with 
the hole. After closing the opening, apply more flux 
to the work and run the hot iron lengthwise to 
smooth the job. 

Soldering Wires. — Clean all insulation from the 
ends to be soldered and scrape the ends bright. Lay 
the ends parallel to each other and, starting at the 
middle of the cleaned portion, wrap the ends around 



192 WELDING 

each other, one being wrapped to the right, the other 
to the left. Hold the hot iron under the twisted joint 
and apply flux to the wire. Then dip the iron in 
the solder and apply to the twisted portion until 
the spaces between the wires are filled with solder. 
Finish by smoothing the joint and cleaning away 
all excess metal by rubbing the hot iron lengthwise. 
The joint should now be covered with a layer of 
rubber tape and this covered with a layer of ordinary 
friction tape. 

Steel and Iron. — Steel surfaces should be cleaned, 
then covered with clear muriatic acid. While the 
acid is on the metal, rub with a stick of zinc and then 
tin the surfaces with the hot iron as directed. Cast 
iron should be cleaned and dipped in strong lye to 
remove grease. Wash the lye away with clean water 
and cover with muriatic acid as with steel. Then 
rub with a piece of zinc and tin the surfaces by 
using resin as a flux. 

It is very difficult to solder aluminum with ordi- 
nary solder. A special aluminum solder should be 
secured, which is easily applied and makes a strong 
joint. Zinc or phosphor tin may be used in place 
of ordinary solder to tin the surfaces or to fill small 
holes or cracks. The aluminum must be thoroughly 
heated before attempting to solder and the flux may 
be either resin or soldering acid. The aluminum must 
be thoroughly cleaned with dilute nitric acid and 
kept hot while the solder is applied by forcible rub- 
bing with the hot iron. 

BRAZING 

This is a process for joining metal parts, very 
similar to soldering, except that brass is used to 



SOLDERING, BRAZING AND THERMIT WELDING 193 

make the joint in place of the lead and zinc alloys 
which form solder. Brazing must not be attempted 
on metals whose melting point is less than that of 
sheet brass. 

Two pieces of brass to be brazed together are heated 
to a temperature at which the brass used in the process 
will melt and flow between the surfaces. The brass 
amalgamates with the surfaces and makes a very 
strong and perfect joint, which is far superior to 
any form of soldering where the work allows this 
process to be used, and in many cases is the equal of 
welding for the particular field in which it applies. 

Brazing Heat and Tools. — The metal commonly 
used for brazing will melt at heats between 1350° 
and 1650° Fahrenheit. To bring the parts to this 
temperature, various methods are in use, using solid, 
liquid or gaseous fuels. "While brazing may be ac- 
complished with the fire of the blacksmith forge, this 
method is seldom satisfactory because of the difficulty 
of making a sufficiently clean fire with smithing coal, 
and it should not be used when anything else is 
available. Large jobs of brazing may be handled 
with a charcoal fire built in the forge, as this fuel 
produces a very satisfactory and clean fire. The 
only objection is in the difficulty of confining the 
heat to the desired parts of the work. 

The most satisfactory fire is that from a fuel gas 
torch built for this work. These torches are simply 
forms of Bunsen burners, mixing the proper quan- 
tity of air with the gas to bring about a perfect 
combustion. Hose lines lead to the mixing tube of 
the gas torch, one line carrying the gas and the other 
air under a moderate pressure. The air line is often 
dispensed with, allowing the gas to draw air into the 



194 WELDING 

burner on the injector principle, much the same as 
with illuminating gas burners for use with incan- 
descent mantles. Valves are provided with which 
the operator may regulate the amount of both gas 
and air, and ordinarily the quality and intensity 
of the flame. 

When gas is not available, recourse may be had 
to the gasoline torch made for brazing. This torch 
is built in the same way as the small portable gasoline 
torches for soldering operations, with the exception 
that two regulating needle valves are incorporated 
in place of only one. 

The torches are carried on a framework, which also 
supports the work being handled. Fuel is forced 
to the torch from a large tank of gasoline into which 
air pressure is pumped by hand. The torches are 
regulated to give the desired flame by means of the 
needle valves in much the same way as with any 
other form of pressure torch using liquid fuel. 

Another very satisfactory form of torch for brazing 
is the acetylene-air combination described in the 
chapter on welding instruments. This torch gives 
the correct degree of heat and may be regulated to 
give a clean and easily controlled flame. 

Regardless of the source of heat, the fire or flame 
must be adjusted so that no soot is deposited on the 
metal surfaces of the work. This can only be accom- 
plished by supplying the exact amounts of gas and 
air that will produce a complete burning of the fuel. 
With the brazing torches in common use two heads 
are furnished, being supplied from the same source 
of fuel, but with separate regulating devices. The 
torches are adjustably mounted in such a way that 
the flames may be directed toward each other, heat- 



SOLDERING, BRAZING AND THERMIT WELDING 19? 

ing two sides of the work at the same time and allow- 
ing the pieces to be completely surrounded with the 
flame. 

Except for the source of heat, tut one tool is 
required for ordinary brazing operations, this being 
a spatula formed by flattening one end of a quarter- 
inch steel rod. The spatula is used for placing the 
brazing metal on the work and for handling the flux 
that is required in this work as in all other similar 
operations. 

Spelter. — The metal that is melted into the joint is 
called spelter. "While this name originally applied 
to but one particular grade or composition of metal, 
common use has extended the meaning until it is 
generally applied to all grades. 

Spelter is variously composed of alloys containing 
copper, zinc, tin and antimony, the mixture employed 
depending on the work to be done. The different 
grades are of varying hardness, the harder kinds 
melting at higher temperatures than the soft ones 
and producing a stronger joint when used. The 
reason for not using hard spelter in all cases is the 
increased difficulty of working it and the fact that 
its melting point is so near to some of the metals 
brazed that there is great danger of melting the work 
as well as the spelter. 

The hardest grade of spelter is made from three- 
fourths copper with one-fourth zinc and is used for 
working on malleable and cast iron and for steel. 
This hard spelter melts at about 1650° and is cor- 
respondingly difficult to handle. 

A spelter suitable for working with copper is made 
from equal parts of copper and zinc, melting at about 
1400° Fahrenheit, 500° below the melting point of 



196 WELDING 

the copper itself. A still softer brazing metal is 
composed of half copper, three-eighths zinc and one- 
eighth tin. This grade is used for fastening brass to 
iron and copper and for working with large pieces of 
brass to brass. For brazing thin sheet brass and 
light brass castings, a metal is used which contains 
two-thirds tin and one-third .antimony. The low 
melting point of this last composition makes it very 
easy to work with and the danger of melting the 
work is ver}^ slight. However, as might be expected, 
a comparatively weak joint is secured, which will not 
stand any great strain. 

All of the above brazing metals are used in powder 
form so that they may be applied with the spatula 
where the joint is exposed on the outside of the 
work. In case it is necessary to braze on the inside 
of a tube or any deep recess, the spelter may be 
placed on a flat rod long enough to reach to the 
farthest point. By distributing the spelter at the 
proper points along the rod it may be placed at the 
right points by turning the rod over after inserting 
into the recess. 

Flux. — In order to remove the oxides produced 
under brazing heat and to allow the brazing metal to 
flow freely into place, a flux of some kind must be 
used. The commonest flux is simply a pure calcined 
borax powder, that is, a borax powder that has been 
heated until practicallv all the water has been driven 
off. 

Calcined borax may also be mixed with about 15 
per cent of sal ammoniac to make a satisfactory 
fluxing powder. It is absolutely necessary to use 
flux of some kind and a part of whatever is used 
should be made into a paste with water so that it 



SOLDERING, BRAZING AND THERMIT WELDING 197 

can be applied to the joint to be brazed before heat- 
ing. The remainder of the powder should be kept 
dry for use during the operation and after the heat 
has been applied. 

Preparing the Work. — The surfaces to be brazed 
are first thoroughly cleaned with files, emery cloth or 
sand paper. If the work is greasy, it should be 
dipped into a bath of lye or hot soda water so that 
all trace of oil is removed. The parts are then placed 
in the relation to each other that they are to occupy 
when the work has been completed. The edges to 
be joined should make a secure and tight fit, and 
should match each other at all points so that the 
smallest possible space is left between them. This 
fit should not be so tight that it is necessary to force 
the work into place, neither should it be loose enough 
to allow any considerable space between the surfaces. 
The molten spelter will penetrate between surfaces 
that water will flow between when the work and spelter 
have both been brought to the proper heat. It is, of 
course, necessary that the two parts have a sufficient 
number of points of contact so that they will remain 
in the proper relative position. 

The work is placed on the surface of the brazing 
table in such a position that the flame from the 
torches will strike the parts to be heated, and with 
the joint in such a position that the melted spelter 
will flow down through it and fill every possible part 
of the space between the surfaces under the action 
of gravity. That means that the edge of the joint 
must be uppermost and the crack to be filled must 
not lie horizontal, but at the greatest slant possible. 
Better than any degree of slant would be to have 
the line of the joint vertical. 



198 WELDING 

The work is braced up or clamped in the proper 
position before commencing to braze, and it is best 
to place fire brick in such positions that it will be 
impossible for cooling draughts of air to reach the 
heated metal should the flame be removed temporarily 
during the process. In case there is a large body of 
iron, steel or copper to be handled, it is often advis- 
able to place charcoal around the work, igniting this 
with the flame of the torch before starting to braze 
so that the metal will be maintained at the correct 
heat without depending entirely on the torch. 

When handling brass pieces having thin sections 
there is danger of melting the brass and causing it 
to flow away from under the flame, with the result 
that the work is ruined. If, in the judgment of the 
workman, this may happen with the particular job 
in hand, it is well to build up a mould of fire clay 
back of the thin parts or preferably back of the 
whole piece, so that the metal will have the necessary 
support. This mould may be made by mixing the 
fire clay into a stiff paste with water and then packing 
it against the piece to be supported tightly enough 
so that the form will be retained even if the metal 
softens. 

Brazing. — "With the work in place, it should be well 
covered with the paste of flux and water, then heated 
until this flux boils up and runs over the surfaces. 
Spelter is then placed in such a position that it will 
run into the joint and the heat is continued or 
increased until the spelter melts and flows in between 
the two surfaces. The flame should surround the 
work during the heating so that outside air is ex- 
cluded as far as is possible to prevent excessive 
oxidization. 



SOLDERING, BRAZING AND THERMIT WELDING 199 

When handling brass or copper, the flame should 
not be directed so that its center strikes the metal 
squarely, but so that it glances from one side or the 
other. Directing the flame straight against the work 
is often the cause of melting the pieces before the 
operation is completed. When brazing two different 
metals, the flame should play only on the one that 
melts at the higher temperature, the lower melting 
part receiving its heat from the other. This avoids 
the danger of melting one before the other reaches 
the brazing point. 

The heat should be continued only long enough to 
cause the spelter to flow into place and no longer. 
Prolonged heating of any metal can do nothing but 
oxidize and w r eaken it, and this practice should be 
avoided as much as possible. If the spelter melts into 
small globules in place of flowing, it may be caused 
to spread and run into the joint by lightly tapping 
the work. More dry flux may be added with the 
spatula if the tapping does not produce the desired 
result. 

Excessive use of flux, especially toward the end 
of the work, will result in a very hard surface on 
all the work, a surface which will be extremely diffi- 
cult to finish properly. This trouble will be present 
to a certain extent anyway, but it may be lessened 
by a vigorous scraping with a wire brush just as 
soon as the work is removed from the fire. If allowed 
to cool before cleaning, the final appearance will not 
be as good as with the surplus metal and scale re- 
moved immediately upon completing the job. 

After the work has been cleaned with the brush 
it may be allowed to cool and finished to the desired 
shape, size and surface by filing and polishing. When 



200 WELDING 

filed, a very thin line of brass should appear where 
the crack was at the beginning of the work. If it 
is desired to avoid a square shoulder and fill in an 
angle joint to make it rounding, the filling is best 
accomplished by winding a coil of very thin brass 
wire around the part of the work that projects and 
then causing this to flow itself or else allow the spelter 
to fill the spaces between the layers of wire. Copper 
wire may also be used for this purpose, the spaces 
being filled with melted spelter. 

THERMIT WELDING 

The process of welding which makes use of the 
great heat produced by oxygen combining with alumi- 
num is known as the Thermit process and was per- 
fected by Dr. Hans Goldschmidt. The process, which 
is controlled by the Goldschmidt Thermit Company, 
makes use of a mixture of finely powdered aluminum 
with an oxide of iron called by the trade name, 
Thermit. 

The reaction is started with a special ignition 
powder, such as barium superoxide and aluminum, 
and the oxygen from the iron oxide combining with 
the aluminum, producing a mass of superheated steel 
at about 5000 degrees Fahrenheit. After the reac- 
tion, which takes from 30 seconds to a minute, the 
molten metal is drawn from the crucible on to the 
surfaces to be joined. Its extreme heat fuses the 
metal and a perfect joint is the result. This process 
is suited for welding iron or steel parts of compara- 
tively large size. 

Preparation. — The parts to be joined are thoroughly 
cleaned on the surfaces and for several inches back 
from the joint, after which they are supported in 



SOLDERTNG, GRAZING AND THERMIT WELDING 201 

place. The surfaces between which the metal will 
flow are separated from y± to 1 inch, depending on 
the size of the parts, but cutting or drilling part of 
the metal away. After this separation is made for 
allowing the entrance of new metal, the effects of 
contraction of the molten steel are cared for by pre- 
heating adjacent parts or by forcing the ends apart 
with wedges and jacks. The amount of this last 
separation must be determined by the shape and 
proportions of the parts in the same way as would 
be done for any other class of welding which heats 
the parts to a melting point. 

Yellow wax, which has been warmed until plastic, 
is then placed around the joint to form a collar, the 
wax completely filling the space between the ends 
and being provided with vent holes by imbedding a 
piece of stout cord, which is pulled out after the 
wax cools. 

A retaining mould (Figure 55) made from sheet 
steel or fire brick is then placed around the parts. 
This mould is then filled with a mixture of one part 
fire clay, one part ground fire brick and one part 
fire sand. These materials are well mixed and 
moistened with enough water so that they will pack. 
This mixture is then placed in the mould, filling the 
space between the walls and the wax, and is packed 
hard with a rammer so that the material forms a 
wall several inches thick between any point of the 
mould and the wax. The mixture must be placed 
in the mould in small quantities and packed tight 
as the filling progresses. 

Three or more openings are provided through this 
moulding material by the insertion of wood or pipe 
forms. One of these openings will lead from the 



202 



WELDING 




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SOLDERING, BRAZING AND THERMIT WELDING 203 

lowest point of the wax pattern and is used for the 
introduction of the preheating flame. Another open- 
ing leads from the top of the mould into this pre- 
heating gate, opening into the preheating gate at a 
point about one inch from the wax pattern. Open- 
ings, called risers, are then provided from each of 
the high points of the wax pattern to the top of the 
mould, these risers ending at the top in a shallow 
basin. The molten metal comes up into these risers 
and cares for contraction of the casting, as well as 
avoiding defects in the collar of the weld. After 
the moulding material is well packed, these gate 
patterns are tapped lightly and withdrawn, except 
in the case of the metal pipes which are placed at 
points at which it would be impossible to withdraw 
a pattern. 

Preheating. — The ends to be welded are brought 
to a bright red heat by introducing the flame from 
a torch through the preheating gate. The torch must 
use either gasoline or kerosene, and not crude oil, as 
the crude oil deposits too much carbon on the parts. 
Preheating of other adjacent parts to care for con- 
traction is done at this time by an additional torch 
burner. 

The heating flame is started gently at first and 
gradually increased. The wax will melt and may 
be allowed to run out of the preheating gate by 
removing the flame at intervals for a few seconds. 
The heat is continued until the mould is thoroughly 
dried and the parts to be joined are brought to the 
red heat required. This leaves a mould just the shape 
of the wax pattern. 

The heating gate should then be plugged with a 
sand core, iron plug or piece of fitted fire brick, and 



204 WELDING 

backed up with several shovels full of the moulding 
mixture, well packed. 

Thermit Metal. — The reaction takes place in a spe- 
cial crucible lined with magnesia tar, which is baked 
at a red heat until the tar is driven off and the 
magnesia left. This lining should last from twelve 




Figure 56. — Thermit Crucible Plug. A, Hard burnt magnesia 
stone ; B, Magnesia thimble ; C. Refractory sand ; D, Metal disc ; E, 
Asbestos washer ; F, Tapping pin 

to fifteen reactions. This magnesia lining ends at 
the bottom of the crucible in a ring of magnesia stone 
and this ring carries a magnesia thimble through 
which the molten steel passes on its way to the mould. 
It will usually be necessary to renew this thimble 
after each reaction. This lower opening is closed 
before filling the crucible with thermit by means of 
a small disc or iron carrying a stem, which is called 
a tapping pin (Figure 56). This pin, F, is placed 



SOLDERING, BRAZING AND THERMIT WELDING 205 

in the thimble with the stem extending down 
through the opening and exposing about two inches. 
The top of this pin is covered with an asbestos, 
washer, E, then with another iron disc, D, and finally 
with a layer of refractory sand. The crucible is tapped 
by knocking the stem of the pin upwards with a 
spade or piece of flat iron about four feet long. 

The charge of thermit is added by placing a few 
handfuls over the refractory sand and then pouring 
in the balance required. The amount of thermit re- 
quired is calculated from the wax used. The w r ax is 
weighed before and after filling the entire space that 
the thermit will occupy. This does not mean only 
the wax collar, but the space of the mould with all 
gates filled with wax. The number of pounds of 
wax required for this filling multiplied by 25 will 
give the number of pounds of thermit to be used. 
To this quantity of thermit should be added 1 per 
cent of pure manganese, 1 per cent nickel thermit and 
15 per cent of steel punchings. 

It is necessary, when more than 10 pounds of 
thermit will be used, to mix steel punchings not 
exceeding % inch diameter by % inch thick with 
the powder in order to sufficiently retard the inten- 
sity of the reaction. 

Half a teaspoonful of ignition powder is placed 
on top of the thermit charge and ignited with a 
storm match or piece of red hot iron. The cover 
should be immediately closed on the top of the 
crucible and the operator should get away to a safe 
distance because of the metal that may be thrown 
out of the crucible. 

After allowing about 30 seconds to a minute for 
the reaction to take place and the slag to rise to the 



206 WELDING 

top of the ciucible, the tapping pin is struck from 
below and the molten metal allowed to run into the 
mould. The mould should be allowed to remain in 
place as long as possible, preferably over night, so 
as to anneal the steel in the w r eld, but in no case 
should it be disturbed for several hours after pouring. 
After removing the mould, drill through the metal 
left in the riser and gates and knock these sections 
off. No part of the collar should be removed unless 
absolutely necessary. 



CHAPTER IX 
OXYGEN PEOCESS FOE EEMOVAL OF CAEBON 

Until recently the methods used for removing car- 
bon deposits from gas engine cylinders were very im- 
practical and unsatisfactory. The job meant dis- 
mantling the motor, tearing out all parts, and scraping 
the pistons and cylinder walls by hand. 

The work was never done thoroughly. It required 
hours of time to do it, and then there was always the 
danger of injuring the inside of the cylinders. 

These methods have been to a large extent super- 
seded by the use of oxygen under pressure. The 
various devices that are being manufactured are 
known as carbon removers, decarbonizers, etc., and 
large numbers of them are in use in the automobile 
and gasoline traction motor industry. 

Outfit. — The oxygen carbon cleaner consists of a 
high pressure oxygen cylinder with automatic reduc- 
ing valve, usually constructed on the diaphragm prin- 
ciple, thus assuring positive regulation of pressure. 
This valve is fitted with a pressure gauge, rubber hose, 
decarbonizing torch with shut off and flexible tube for 
insertion into the chamber from which the carbon is to 
be removed. 

There should also be an asbestos swab for swabbing 
out the inside of the cylinder or other chamber with 
kerosene previous to starting the operation. The 
action consists in simply burning the carbon to a fine 
dust in the presence of the stream of oxygen, this dust 
being then blown out. 

207 



208 WELDING 

Operation. — The following are instructions for oper- 
ating the cleaner : — 

(1) Close valve in gasoline supply line and start 
the motor, letting it run until the gasoline is ex- 
hausted. 

(2) If the cylinders be T or L head, remove either 
the inlet or the exhaust valve cap, or a spark plug if 
the cap is tight. If the cylinders have overhead valves, 
remove a spark plug. If any spark plug is then re- 
maining in the cylinder it should be removed and an 
old one or an iron pipe plug substituted. 

(3) Eaise the piston of the cylinder first to be 
cleaned to the top of the compression stroke and con- 
tinue this from cylinder to cylinder as the work pro- 
gresses. 

(4) In motors where carbon has been burned hard, 
the cylinder interior should then be swabbed with 
kerosene before proceeding. Work the swab, saturated 
with kerosene, around the inside of the cylinder until 
all the carbon has been moistened with the oil. This 
same swab may be used to ignite the gas in the cyl- 
inder in place of using a match or taper. 

(5) Make all connections to the oxygen cylinder. 

(6) Insert the torch nozzle in the cylinder, open the 
torch valve gradually and regulate to about two lbs. 
pressure. Manipulate the nozzle inside the cylinder 
and light a match or other flame at the opening so 
that the carbon starts to burn. Cover the various 
points within the cylinder and when there is no 
further burning the carbon has been removed. The 
regulating and oxygen tank valves are operated in 
exactly the same way as for welding as previously 
explained. 

It should be carefully noted that when the piston is 



OXYGEN PROCESS FOR REMOVAL OF CARBON 209 

up, ready to start the operation, both valves must be 
closed. There will be a considerable display of sparks 
while this operation is taking place, but they will not 
set fire to the grease and oil. Care should be used to 
see that no gasoline is about. 



INDEX 



PAGE 

Acetylene 42 

filtering 78 

generators 60 

in tanks 49 

piping 79 

properties of 46 

purification of 47 

Acetylene-air torches 104 

Air 36 

oxygen from '. 35 

Alloys 11, 20 

table of 137 

Alloy steel 15 

Aluminum 17 

alloys 24 

welding 130 

Annealing 27 

Anvil 172 

Arc welding, electric 160 

machines 166 

Asbestos, use of, in welding 58 

Babbitt 24 

Bending pipes and tubes 176 

Bessemer steel 16 

Beveling 115, 116 

Brass 22 

welding 132 

Brazing 155, 188, 192, 198 

electric 155 

heat and tools 193 

spelter 195 

Bronze 23 

welding 132 

Butt welding 151 

211 



212 INDEX 

PAGE 

Calcium carbide 43 

Carbide 43 

storage of, Fire Underwriters' Eules 45 

to water generator 64 

Carbon removal 33 

by oxygen process 207 

Case hardening steel 32 

Cast iron 12 

welding 150 

Champfering 113 

Charging generator 69 

Chlorate of potash oxygen 41 

Conductivity of metals 140 

Copper 18 

alloys 22 

welding 131 

Crucible steel 16 

Cutting, oxy-acetylene 33 

torches 103 

Dissolved acetylene 50 

Electric arc welding 160 

Electric welding 142 

troubles and remedies 155 

Expansion of metals 141 

Flame, welding 121 

Fluxes 54, 180 

for brazing 196 

for soldering 189 

Forge 170 

fire 171 

practice 173 

tools 171 

tuyere construction of 170 

welding 182 

welding preparation 178 

welds, forms of 184 

Forging 170 

Gas holders 66, 77 

Gases, heating power of 139 

Generator, acetylene 60 

carbide to water 64 

construction 68 



INDEX 213 

Generator page 

location of 84 

operation and care of 71 

overheating 62 

requirements 61 

water to carbide 63 

German silver 24 

Gloves 56 

Goggles 56 

Hand forging 170 

Hardening steel 27 

Heat treatment of steel 25 

Hildebrandt process 39 

Hose 58 

Injectors, adjuster 99 

Iron 11 

cast 12 

grades of 14 

malleable cast 13 

wrought 13 

Jump weld 185 

Lap welding 154 

Lead 18 

Linde process 38 

Liquid air oxygen 38 

Magnalium 24 

Malleable iron 13 

welding 128 

Melting points of metals 139 

Metal alloys, table of 137 

Metals 11 

characteristics of 125 

conductivity of 140 

expansion of 141 

heat treatment of 11 

melting points of 139 

tensile strength of 140 

weight of 141 

Nickel 20 

Nozzle sizes, torch 102 



214 INDEX 

PAGE 

Open hearth steel 17 

Oxy-acetylene cutting 33 

welding practice 106 

Oxygen 35 

cylinders 39 

weight of 39 

Pipes, bending 176 

Platinum 20 

Preheating 106, 203 

Removal of carbon by oxygen process 207 

Eesistance method of electric welding 142 

Eestoration of steel 132 

Eods, welding 52 

Safety devices 80 

Scarfing 179 

Solder 24 

Soldering 188 

flux 188 

holes 191 

seams 191 

steel and iron 192 

wires 191 

Spelter 195 

Spot welding 143, 154 

Steel 14 

alloys 15, 21 

Bessemer 16 

crucible 16 

heat treatment of 25 

open hearth 17 

restoration of 132 

tensile strength of 15 

welding 150 

Strength of metals 140 

Tank valves 85 

Tapering 114 

Tables of welding information 136-141 

Tempering steel 30 

Thermit metal 204 

preheating 203 

preparation 200 

welding 188, 200 



INDEX 213 

PAGE 

Tin 19 

Torch 90 

acetylene-air 104 

care 101 

construction 100 

cutting 103 

high pressure 96 

low pressure 98 

medium pressure 97 

nozzles 102 

practice 34, 118 

Valves, regulating 86 

tank 85 

Water 37 

to carbide generator 63 

Welding aluminum 130 

brass 132 

bronze 132 

butt 151 

cast iron 127 

copper 131 

electric 142 

electric arc 160 

flame 121 

forge 182 

information and tables 135-141 

instruments 85 

lap 154 

malleable iron 128 

materials 33 

practice, oxy-acetylene 106 

rods 52 

spot 143, 154 

steel .*, . . 129 

table 57 

thermit 188, 200 

torches 90 

various metals 125 

wrought iron 129 

Wrought iron 13 

welding 129 

Zinc 19 



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Corners, Red Edges. Price, $2.00. 

• 

At the present time nearly all automobile 
troubles or breakdowns may, in almost 
every case, be traced to the lack of knowl- 
edge cr carelessness of tbe owner or opera- 
tor of the car, rather than to the car itself. 
The automobile hand book is a work of 
p actical information for the use of owners, 
operators and automobile mechanics, giv- 
ing full and concise information on all 
quf stions relating to the construction, care 
and operai on of gasoline and electric auto- 
mobiles, including road troubles, motor 
troubles, -rbureter troubles, ignition 
troubles, battery troubles, clutch troubles, 
starting troubles. With numerous tables, 
useful rules and formula?, wiring diagrams 
and over329illustrations. 

Special efforts have been put forth to 
treat the subjects of ignition, and igni- 
tion devices, in a manner befitting their 
importance. A large section has been 
devoted to t ese subjects, including bat- 
teries, primary and secondary, magnetos, 
carburators, spark plugs, and in fact all devices used in connection with 
the production of the spark. Power transmissio is thoroughly discussed, 
and the various systems of transmitting the power from the motor to the 
driving axle are analyzed and compared. 

The perusal of this work for a few minutes when troubles occur, will 
often not only save time, money, and worry, but give greater confidence 
in the car, with regard to its going qualities on the road, when properly 
and intelligently cared for. 

A WORD TO THE WISE 

The time is at hand when any person caring for and operating any 
kind of self-propelling vehicle in a public or private capacity, will have to 
undergo a rigid examination before a state board of examiners and secure 
a license before they can collect their salary or get employment. 

Already New York State has enacted such - law and before long, with 
a positive certainty every state in the Union will pass such an ordinance 
for the protection of life and property. 

Remember this is a brand new book from cover to cover, just irom 
the press — New Edition — and must not be confounded with any former 
editions of this popular work. 

Sent prepaid to any address upon receipt of price 

FREDERICK J. DRAKE & CO., Publishers 

1325 Michigan Avenue. - • • CHICAGO, U.S. A. 



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